Compositions and methods for the treatment of disorders related to frataxin deficiency

Abstract

The disclosure relates to compositions and methods for, inter alia, altering, e.g., enhancing, the level of FXN protein via delivery using an adeno-associated viral (AAV) capsid variant. The compositions and methods of the present disclosure are useful, inter alia, for the treatment of subjects who have, have been diagnosed with having, or are at risk of having a disorder associated with frataxin (FXN) deficiency, e.g., Friedreich's Ataxia (FA), or at least one symptom thereof.

Description

COMPOSITIONS AND METHODS FOR THE TREATMENT OF DISORDERSRELATED TO FRATAXIN DEFICIENCYRELATED APPLICATIONS

[0001] This application claims the benefit of and priority to US Provisional Application Serial No. 63 / 606,275, filed December 5, 2023.SEQUENCE LISTING

[0002] The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing file, entitled 14640_0102-00304_SL.xml. was created on September 18, 2024, and is 1 ,772.400 bytes in size. The information in electronic format of the Sequence Listing is incorporated herein by reference in its entirety.FIELD

[0003] Described herein are compositions and methods relating to adeno-associated virus (AAV) viral particles for the delivery' of polynucleotides, e.g.. polynucleotides encoding a frataxin (FXN) protein for use in the treatment of Friedreich’s Ataxia (FA). In some embodiments, compositions described herein may be used to treat a subject in need thereof, such as a human subject diagnosed with FA, or as a research tool in the study of diseases or conditions in cells or animal models of FA.BACKGROUND

[0004] Friedreich’s Ataxia (FA) is an autosomal recessive inherited disease that causes progressive damage to the nervous system. See Parkinson et al., Journal of Neurochemistry, 2013, 126 (Suppl. 1), 103-117, the contents of which are herein incorporated by reference in their entirety. FA ty pically results from the degeneration of nervous tissue in the spinal cord due to reduced expression of the mitochondrial protein frataxin (FXN; also known as, e.g., CyaY, FA, FARR, FRDA, and X25) in sensory neurons that direct muscle movement of the arms and legs. See Koeppen, Arnulf; J Neurol Sci., 2011, April 15;303(1-2): 1-12. Onset usually occurs at puberty or by age 25. See Campuzano, et al., Science, 271.5254 (Mar 8, 1996): 1423. Initial symptoms of FA include poor coordination such as gait disturbance, poor balance, leg weakness, decreased walking, impaired coordination, dysarthria, nystagmus, impaired sensation, kyphoscoliosis, and foot deformities. See Parkinson et al., Journal of Neurochemistry. 2013. 126 (Suppl. 1), 103-117. FA is also associated with scoliosis, heart disease, and diabetes. The disease generally progresses until a wheelchair is required for mobility. Incidence of FA among Caucasian populations is between about 1 in 20.000 and about 1 in 50,000, with a deduced carrier frequency of about 1 in 120 in European populations. See Nageshwaran and Festenstein, Frontiers in Neurology, Vol.6, Art. 262 (2015); Campuzano, et al.. Science. 271.5254 (Mar 8, 1996): 1423. the contents of which are herein incorporated by reference in their entirety'. The expansion of an intronic GAA triplet repeat in the FXN gene is the genetic cause of reduced expression of FXN resulting in FA. See Parkinson et al.,Journal of Neurochemistry , 2013, 126 (Suppl. 1), 103-117. Over time, the deficiency causes the aforementioned symptoms, as well as frequent fatigue due to effects on cellular metabolism. Currently, omaveloxolone (Skyclarys®) is the only FDA approved treatment for FA. Omaveloxolone is a semisynthetic oleanane triterpenoid that activates Nrf2, a master transcription factor that regulates genes with antioxidative. anti-inflammatoiy, and mitochondrial bioenergetic properties. See Reisman et al. (2019) Drug Des Devel Ther. 13:1259-1270. While gene therapy constructs for delivering a frataxin protein have been described in the arm, there remains a need to develop improved constructs for better targeting of the appropriate tissues in the body.

[0005] Adeno-associated viruses (AAVs) have emerged as a widely studied and utilized viral particles for delivery of therapeutically effective polypeptides to mammalian cells. See, e.g.. Tratschin et al., Mol. Cell Biol., 5(11):3251-3260 (1985) and Grimm et al., Hum. Gene Ther., 10(15):2445-2450 (1999), the contents of each of which are herein incorporated by reference in their entirety.

[0006] There remains a need for effective methods of treatment using AAV capsids that are capable of delivering FXN to a target cell or tissue, e.g., a CNS cell or tissue.SUMMARY

[0007] The present disclosure addresses these challenges by providing AAV-based compositions comprising AAV capsid variants and methods for treating Friedreich’s Ataxia (FA) or at least one symptom thereof in subjects. Disclosed herein are compositions and methods directed to AAV-based gene delivery of FXN (e.g., human FXN) to ameliorate loss-of-function and to improve FXN expression (e.g., in the brain, e.g., in neurons). In some embodiments, the compositions and methods can be used to slow, halt, or reverse symptoms of FA.

[0008] In some aspects, the present disclosure provides an adeno-associated virus (AAV) particle comprising an AAV capsid variant and a viral genome, wherein the viral genome comprises a frataxin (FXN)-encoding sequence and the AAV capsid variant comprises an ammo acid sequence having the formula [N1]-[N2]-[N3] (SEQ ID NO: 4681) in loop VIII. wherein [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682); [Nl] comprises amino acids Xi, X2, X3, and X4, wherein X4 is Q. K, E, S. P, R, N. or H; and / or [N3] comprises amino acids Xs, Xs, and X?, wherein X5 is I. V, T, M, S, N. L, or F. In some embodiments, the AAV capsid variant is an AAV9 capsid variant. In some embodiments, the AAV capsid variant comprises an amino acid sequence that is at least 95% identical to positions 203-736 of the amino acid sequence of SEQ ID NO: 981. In some embodiments, loop VIII is present at amino acids comprising those corresponding to positions 580-599 of the amino acid sequence of SEQ ID NO: 981.

[0009] In some embodiments, Xi is T, S, R, A, I, C, N. K, L, or Q; X2is N, T, G, V, S. Y, K, I, H, D, or F; and X3is T, N, K, D, I, S, P. A, Y, E, V, L. M, R. H, Q, or C. In some embodiments, X6is A, Y, P, N, S, T, G, E, V, W, F, or Q; and X7is Q, G, N, K, H, R, E, L, P, or M.

[0010] In some embodiments, [Nl] comprises the amino acid sequence of TNTQ (SEQ ID NO: 4688). In some embodiments, [N3] comprises the amino acid sequence of IAQ. In some embodiments, [N1]-N2]-[N3] comprises the amino acid sequence of TNTQDWHRIAQ (SEQ ID NO: 343).[OH] In some embodiments, [Nl] is present at amino acids comprising those corresponding to positions 580-599 of the amino acid sequence of SEQ ID NO: 981, [N2] is present at amino acids corresponding to positions 586-589 of the amino acid sequence of SEQ ID NO: 981, and [N3] is present at amino acids corresponding to positions 590-592 of the amino acid sequence of SEQ ID NO: 981.

[0012] In some embodiments, the AAV capsid variant further comprises [N4] comprising amino acids X8, X9, Xio, and Xu, wherein: X8is T. S, N, P. A, or I; X9is G, N, D, R. V, A. S, or Q: Xio is W, S, C, R, L. or G; and / or Xu is V, A. S, I, C, G. D, F, L. or T. In some embodiments, [N4] comprises the amino acid sequence of TGWV (SEQ ID NO: 5066). In some embodiments, [N4] is present at amino acids corresponding to positions 593-596 of the amino acid sequence of SEQ ID NO: 981.

[0013] In some embodiments, [N1]-[N2]-[N3]-[N4] comprises the amino acid sequence of TNTQDWHRIAQTGWV (SEQ ID NO: 201).

[0014] In some aspects, the present disclosure provides an AAV particle comprising a viral genome comprising a FXN-encoding sequence and an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to positions 203-736 of the amino acid sequence of SEQ ID NO: 981, wherein the AAV capsid variant comprises: T at an amino acid corresponding to position 584 of the amino acid sequence of SEQ ID NO: 981; D at an amino acid corresponding to position 586 of the amino acid sequence of SEQ ID NO: 981; W at an amino acid corresponding to position 587 of the amino acid sequence of SEQ ID NO: 981; H at an amino acid corresponding to position 588 of the amino acid sequence of SEQ ID NO: 981; R at an amino acid corresponding to position 589 of the amino acid sequence of SEQ ID NO: 981; and I at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 981.

[0015] In some aspects, the present disclosure provides an AAV particle comprising a viral genome comprising a FXN-encoding sequence and an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to positions 138-736 of the amino acid sequence of SEQ ID NO: 981. In some aspects, the present disclosure provides an AAV particle comprising a viral genome comprising a FXN-encoding sequence and an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to positions 138-736 of the amino acid sequence of SEQ ID NO: 981, wherein the AAV capsid variant comprises: T at an amino acid corresponding to position 584 of the amino acid sequence of SEQ ID NO: 981; D at an amino acid corresponding to position 586 of the amino acid sequence of SEQ ID NO: 981; W at an amino acid corresponding to position 587 of the amino acid sequence of SEQ ID NO: 981; H at an amino acid corresponding to position 588 of the amino acid sequence of SEQ ID NO: 981; R at an amino acid corresponding to position 589 of the amino acid sequence of SEQ ID NO: 981; and I at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 981.

[0016] In some aspects, the present disclosure provides an AAV particle comprising a viral genome comprising a FXN-encoding sequence and an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 981. In some aspects, the present disclosure provides an AAV particle comprising a viral genome comprising a FXN-encoding sequence and an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 981, wherein the AAV capsid variant comprises: T at an amino acid corresponding to position 584 of the amino acid sequence of SEQ ID NO: 981; D at an amino acid corresponding to position 586 of the amino acid sequence of SEQ ID NO: 981; W at an amino acid corresponding to position 587 of the amino acid sequence of SEQ ID NO: 981; H at an amino acid corresponding to position 588 of the amino acid sequence of SEQ ID NO: 981; R at an amino acid corresponding to position 589 of the amino acid sequence of SEQ ID NO: 981; and I at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 981.

[0017] In some aspects, the present disclosure provides an AAV particle comprising a viral genome comprising a FXN-encoding sequence and an AAV capsid variant, wherein the AAV capsid variant comprises: (i) an amino acid sequence that is at least 99% identical to the amino acid sequence of SEQ ID NO: 981 : (ii) an amino acid sequence that is at least 99% identical to positions 138-736 of the amino acid sequence of SEQ ID NO: 981; and / or (iii) an amino acid sequence that is at least 99% identical to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

[0018] In some embodiments, the AAV capsid variant comprises the amino acid sequence of TQDWHRI (SEQ ID NO: 941). In some embodiments, the AAV capsid variant comprises at least 8, at least 9, or at least 10 consecutive amino acids from the amino acid sequence of TNTQDWHRI AQ (SEQ ID NO: 343). In some embodiments, the AAV capsid variant comprises the amino acid sequence of TNTQDWHRI AQ (SEQ ID NO: 343) present at amino acids corresponding to positions 582-592 of the amino acid sequence of SEQ ID NO: 981. In some embodiments, the amino acid sequence of TQDWHRI (SEQ ID NO: 941) or TNTQDWHRIAQ (SEQ ID NO: 343) is present in loop VIII, wherein loop VIII comprises amino acids 580-599 of the amino acid sequence of SEQ ID NO: 981.

[0019] In some embodiments, the AAV capsid variant comprises: (i) the amino acid sequence of SEQ ID NO: 981; (ii) the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981; and / or (iii) the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

[0020] In some embodiments, the FXN protein encoded by the FXN-encoding sequence is not a cynomolgus monkey FXN protein. In some embodiments, the FXN-encoding sequence encodes a human FXN protein. In some embodiments, the human FXN protein comprises the amino acid sequence of any one of SEQ ID NOs: 5124-5126 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the FXN-encoding sequence encodes a human FXN protein. In some embodiments, the human FXN protein comprises the amino acidsequence of SEQ ID NO: 1825 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the FXN protein is a wildt pe human FXN protein.

[0021] In some embodiments, the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto.

[0022] In some embodiments, the viral genome further comprises a promoter operably linked to the FXN-encoding sequence. In some embodiments, the promoter comprises a human elongation factor 1α- subunit (EFlα) promoter, a cytomegalovirus (CMV) immediate-early enhancer and / or promoter, a chicken -actin (CBA) promoter, a CAG promoter, a β glucuronidase (GUSB) promoter, a ubiquitin C (UBC) promoter, a neuron-specific enolase (NSE) promoter, a platelet-derived growth factor (PDGF) promoter, a platelet-derived growth factor B-chain (PDGF- ) promoter, a intercellular adhesion molecule 2 (ICAM-2) promoter, a synapsin (Syn) promoter, a methyl-CpG binding protein 2 (MeCP2) promoter, a Ca2+ / calmodulin-dependent protein kinase II (CaMKII) promoter, a metabotropic glutamate receptor 2 (mGluR2) promoter, a neurofilament light chain (NFL) promoter, a neurofilament heavy' chain (NFH) promoter, a -globin minigene n 2 promoter, a preproenkephalin (PPE) promoter, a enkephalin (Enk) and excitatory' amino acid transporter 2 (EAAT2) promoter, a glial fibrillary acidic protein (GFAP) promoter, a myelin basic protein (MBP) promoter, a cardiovascular promoter (e.g., aMHC, cTnT, and CMV-MLC2k), a liver promoter (e.g., hAAT, TBG), a skeletal muscle promoter (e.g., desmin, MCK, C512), or a functional fragment or truncation thereof. In some embodiments, the promoter is a CMV promoter or CBA promoter, or a functional fragment or truncation of a CMV promoter or CBA promoter. In some embodiments, the promoter is a truncated CBA promoter. In some embodiments, the truncated CBA promoter is 50-400 nucleotides in length, e.g., 100-332 nucleotides in length. In some embodiments, the promoter comprises (i) the nucleotide sequence SEQ ID NO: 1738 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (ii) the nucleotide sequence of SEQ ID NO: 1740 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; or (iii) the nucleotide sequence of SEQ ID NO: 1742 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the promoter is a truncated CMV promoter. In some embodiments, the truncated CMV promoter is 50-300 nucleotides in length. In some embodiments, the promoter comprises the nucleotide sequence of SEQ ID NO: 1750 or a nucleotide sequence that is at least 90% identical (e.g..at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

[0023] In some embodiments, the viral genome further comprises a nucleotide sequence encoding a miRNA (miR) binding site that modulates expression of the encoded FXN protein in a cell or tissue of the liver. In some embodiments, the viral genome encodes 3 copies of the miR binding site. In some embodiments, the 3 copies of the miR binding site are identical. In some embodiments, the miR binding site is a miR122 binding site. In some embodiments, the miR122 binding site is encoded by the nucleotide sequence of SEQ ID NO: 1827 or a nucleotide sequence comprising one. two, three, or up to four substitutions relative thereto; or the viral genome encodes 3 copies of the miR122 binding site, wherein the nucleotide sequence encoding the 3 copies of the miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence comprising one. two, three, four, five, six, seven, eight, nine, or up to ten substitutions relative thereto.

[0024] In some embodiments, the viral genome further comprises at least one inverted terminal repeat (ITR) region. In some embodiments, the at least one ITR region comprises an AAV2 ITR. In some embodiments, the viral genome comprises a 5’ ITR region and a 3’ ITR region. In some embodiments, the 5’ ITR region and 3’ ITR region are each an AAV2 ITR. In some embodiments, the 5' ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or the 3' ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

[0025] In some embodiments, the viral genome further comprises an intron / exon region comprising an intron region and / or an exon region. In some embodiments, the intron / exon region comprises an immediate-early 1 (icl) intron region and / or a human bcta-globin (hBglobin) intron 2 region; and / or an iel exon region and / or an hBglobin exon region. In some embodiments, the intron region comprises the nucleotide sequence of SEQ ID NO: 1819 or a nucleotide sequence that is at least 90% identical (e g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or comprises the nucleotide sequence of SEQ ID NO: 1820 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the exon region comprises the nucleotide sequence of SEQ ID NO: 1817 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; and / or comprises the nucleotide sequence of SEQ ID NO: 1821 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%, at least 98%. or at least 99% identical) thereto. In some embodiments.die intron / exon region comprises die nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence diat is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

[0026] In some embodiments, die viral genome further comprises a polyadenylation (poly A) region. In some embodiments, the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

[0027] In some embodiments, die viral genome comprises the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

[0028] In some embodiments, the viral genome comprises the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

[0029] In some embodiments, the viral genome comprises the nucleotide sequence of SEQ ID NO:1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto.

[0030] In some embodiments, the viral genome comprises the nucleotide sequence of SEQ ID NO:1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) diereto.

[0031] In some embodiments, the viral genome comprises: (i) a 5’ inverted terminal repeat (ITR) region; (ii) a promoter; (iii) the FXN-cncoding sequence, wherein the FXN-cncoding sequence comprises die nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and (iv) a 3‘ ITR region.

[0032] hi some embodiments, die viral genome comprises: (i) a 5’ inverted terminal repeat (ITR) region; (ii) a promoter: (iii) the FXN-encoding sequence, wherein the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g.. at least 80%, at least 85%, at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; (iv) a nucleotide sequence encoding at least one miR122 binding site: and (v) a 3’ ITR region.

[0033] In some embodiments, the viral genome comprises: (i) a 5’ inverted terminal repeat (ITR) region; (ii) a promoter: (iii) an intron / exon region; (iv) the FXN-encoding sequence, wherein the FXN- encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence thatis at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) diereto; (v) a nucleotide sequence encoding at least one miR122 binding site; and (vi) a 3’ ITR region.

[0034] In some embodiments, the viral genome comprises: (i) a 5’ inverted terminal repeat (ITR) region; (ii) a promoter: (iii) an intron / exon region; (iv) the FXN-encoding sequence, wherein the FXN- encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (v) a nucleotide sequence encoding at least one miR122 binding site; (vi) a poly adenylation (poly A) region; and (vii) a 3 ’ ITR region.

[0035] In some embodiments, the viral genome comprises: (i) a 5’ inverted terminal repeat (ITR) region; (ii) a promoter: (iii) an intron / exon region; (iv) the FXN-encoding sequence, wherein the FXN- encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; (v) a nucleotide sequence encoding at least one miR122 binding site; (vi) a polyadenylation (poly A) region; (vii) a filler sequence; and (viii) a 3 ’ ITR region.

[0036] In some embodiments, (i) the 5 ’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; (ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1742 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) tiiereto; (iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) diereto; (iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (vi) the polyA region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; and / or (vii) the 3’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the viral genome further comprises a filler sequence comprising die nucleotide sequence of SEQ ID NO: 1841 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the poly A region and 5‘ to the 3’ ITR.

[0037] In some embodiments, (i) the 5 ’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; (ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1750 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; (iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; (iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; (v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (vi) the polyA region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or (vii) the 3’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1840 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the polyA region and 5’ to the 3’ ITR.

[0038] In some embodiments, (i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; (ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1738 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%. at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (iii) the intron / exon region comprises die nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (vi) the polyA region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%. at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; and / or (vii) the 3’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%. at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1838 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the polyA region and 5’ to the 3’ ITR.

[0039] In some embodiments, (i) the 5 ’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; (ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1740 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence comprising SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (vi) the polyA region comprises the nucleotidesequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or (vii) the 3’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto. In some embodiments, the viral genome further comprises a fdler sequence comprising the nucleotide sequence of SEQ ID NO: 1839 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto, optionally wherein the fdler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.

[0040] In some embodiments, the viral genome comprises: (i) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%. at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; (ii) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; (iii) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; or (iv) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto. In some embodiments, (i) the 5' ITR region comprises the nucleotide sequence of SEQ ID NO: 1811; (ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1742; (iii) the intron / exon region comprises die nucleotide sequence of SEQ ID NO: 1816; (iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824; (v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826; (vi) the polyA region comprises the nucleotide sequence of SEQ ID NO: 1828; and (vii) the 3' ITR region comprises the nucleotide sequence of SEQ ID NO: 1812. In some embodiments, the viral genome further comprises a fdler sequence comprising the nucleotide sequence of SEQ ID NO: 1841, wherein the filler sequence is positioned 3’ to the polyA region and 5’ to the 3’ ITR region.

[0041] In some embodiments, die viral genome comprises the nucleotide sequence of SEQ ID NO: 1797. In some embodiments, the viral genome consists of the nucleotide sequence of SEQ ID NO: 1797.

[0042] In some aspects, the present disclosure provides an AAV particle comprising an AAV capsid variant and a viral genome comprising a frataxin (FXN)-encoding sequence, wherein the AAV capsid variant comprises: (i) the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; (ii) the amino acid sequenceaccording to positions 138-736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or (iii) the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and the viral genome comprises: (a) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (b) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; (c) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; or (d) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto.

[0043] In some aspects, the present disclosure provides an AAV particle comprising a viral genome comprising the nucleotide sequence of SEQ ID NO: 1824 and an AAV capsid variant comprising the amino acid sequence of SEQ ID NO: 981, the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981, and / or the amino acid sequence according to positions 203- 736 of the amino acid sequence of SEQ ID NO: 981. In some embodiments, the viral genome comprises tire nucleotide sequence of SEQ ID NO: 1797.

[0044] In some embodiments, the viral genome is single-stranded.

[0045] In some aspects, the present disclosure provides a cell comprising an AAV particle provided herein. In some embodiments, the cell is a mammalian cell (e.g., an HEK293 cell), an insect cell (e.g., an Sf9 cell), or a bacterial cell.

[0046] In some aspects, the present disclosure provides a method of making an AAV particle provided herein. In some embodiments, the method comprises (i) providing a cell comprising a viral genome comprising a frataxin (FXN)-encoding sequence and a nucleic acid encoding an AAV capsid variant; and (ii) incubating the cell under conditions suitable to encapsulate the viral genome in the AAV capsid variant; thereby making the AAV particle.

[0047] In some embodiments of the method of making an AAV particle, the viral genome comprises (i) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (ii) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%.at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; (iii) die nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) tiiereto; or (iv) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto: and the AAV capsid variant comprises (a) the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; (b) die amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence drat is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or (c) the amino acid sequence according to positions 203- 736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto.

[0048] In some embodiments of the method of making an AAV particle, the viral genome comprises (i) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; (ii) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; (iii) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; or (iv) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 981, the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981, and / or the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

[0049] In some embodiments of the method of making an AAV particle, the viral genome comprises the nucleotide sequence of SEQ ID NO: 1797 and the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 981, the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981, and / or the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

[0050] In some embodiments, the method of making an AAV particle further comprises, prior to step (i), introducing a nucleic acid comprising the viral genome into the cell. In some embodiments, the method further comprises, prior to step (i), introducing the nucleic acid encoding the AAV capsid variant into the cell. In some embodiments, the cell comprises a mammalian cell (e.g., an HEK293 cell), an insect cell (e.g., an S19 cell), or a bacterial cell.

[0051] In some aspects, the present disclosure provides a pharmaceutical composition comprising an AAV particle provided herein and a pharmaceutically acceptable excipient.

[0052] In some aspects, the present disclosure provides a method of delivering an AAV particle encoding a frataxin (FXN) protein to a cell, comprising administering an effective amount of a pharmaceutical composition or AAV particle provided herein. In some embodiments, the cell is in a subject. In some embodiments, the subject has, has been diagnosed with having, or is at risk of having a disorder associated with FXN deficiency or at least one symptom thereof. In some embodiments, the disorder is Friedreich’s Ataxia (FA).

[0053] In some aspects, the present disclosure provides a method of treating a subject having or diagnosed with having a disorder associated with frataxin (FXN) deficiency or at least one symptom thereof, comprising administering to the subject an effective amount of a pharmaceutical composition or AAV particle provided herein. In some embodiments, the subject has. has been diagnosed with having, or is at risk of having Friedreich’s Ataxia (FA) or at least one symptom thereof.

[0054] In some aspects, the present disclosure provides a method of treating a subject having or diagnosed with having a disorder or at least one symptom thereof, wherein the disorder is FA, comprising administering to the subject an effective amount of a pharmaceutical composition or AAV particle provided herein.

[0055] In some embodiments, the treating results in prevention of progression of the disorder or at least one symptom thereof in the subject. In some embodiments, the treating results in amelioration of at least one symptom of the disorder. In some embodiments, the at least one symptom comprises impaired sensory functions, impaired motor function (e g., ataxia and / or involuntary movements), fatigue, chronic pain, seizures, impaired speech, sleep disturbances, metabolic disorders (e.g., diabetes), and / or increased spasticity. In some embodiments, the treating stabilizes, slows the progression of, or improves the subject's disorder as determined by the modified Friedreich Ataxia Rating Scale (mFARS), the Scale for the Assessment and Rating of Ataxia (SARA), and / or the International Cooperative Ataxia Rating Scale (ICARS). In some embodiments, the treating slows the subject’s progression of the disorder as measured by mFARS, SARA, and / or ICARS relative to an individual with the disorder who has not been administered the pharmaceutical composition or the AAV particle.

[0056] In some embodiments, the subject is a human.

[0057] In some embodiments, the AAV particle or the pharmaceutical composition is delivered to a cell or tissue of the central nervous system (CNS) in the subject. In some embodiments, the cell or tissue of the CNS is a cell or tissue of the amygdala, brainstem, caudate, central grey, cerebellum (e.g.. Purkinjecell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary' complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g.. cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region). In some embodiments, the AAV particle or the pharmaceutical composition is delivered to the subject via intravenous administration.

[0058] In some embodiments, a method of delivery or treatment provided herein further comprises evaluating, e.g., measuring, the level of FXN expression, e.g., FXN gene. FXN mRNA, and / or FXN protein expression, in the subject, e.g., in a cell, tissue, or fluid, of the subject. In some embodiments, die level of FXN protein expression is measured by an enzyme-linked immunosorbent assay (ELISA), a Western blot, an immunohistochemistry assay, or a frataxin biofluid assay. In some embodiments, evaluating the subject’s level of FXN expression is performed before and / or after administration of the pharmaceutical composition or AAV particle, optionally wherein the subject’s level of FXN expression before administration is compared to the subject’s level of FXN expression after administration. In some embodiments, the cell or tissue in which the level of FXN expression is evaluated is a cell or tissue of the CNS. In some embodiments, the cell or tissue of the CNS is a cell or tissue of the amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory' cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary' complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region). In some embodiments, the method of delivery' or treatment further comprises evaluating the level of FXN expression, e.g., FXN gene, FXN mRNA, and / or FXN protein expression, in a peripheral cell or tissue of the subject. In some embodiments, the peripheral cell or tissue is a cell or tissue of the heart and / or muscle. In some embodiments, the muscle is skeletal muscle.

[0059] In some embodiments, the subject’s level of FXN protein expression after administration is increased relative to the subject’s level of FXN protein expression before administration.

[0060] hi some embodiments, tire method of delivery or treatment further comprises evaluating, e.g., measuring, the level of FXN protein activity' in the subject.

[0061] In some embodiments, administration of the pharmacal composition or AAV particle results in an increase in: (i) the level of FXN protein or FXN gene expression in a cell, tissue, (e.g., a cell or tissue of the CNS. e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g.. frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g..cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region), or a cell or tissue outside of the CNS, e.g., muscle (e.g., skeletal muscle)), and / or fluid (e.g., CSF and or serum), of the subject relative to baseline and / or relative to the level of FXN protein or FXN gene expression in a cell, tissue, or fluid of an individual with a disorder associated with FXN deficiency who has not been administered the pharmaceutical composition or AAV particle; (ii) the number and / or level of viral genomes (VG) per cell in a CNS tissue (e g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g.. cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region)) or non-CNS tissue (e.g., muscle (e.g.. skeletal muscle)) of the subject relative to the number and / or level of VG per cell in a peripheral tissue of the subject; and / or (iii) the level of FXN activity in a cell, tissue, (e.g., a cell or tissue of the CNS, e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g.. frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region), or a cell or tissue outside of the CNS, e.g., muscle (e.g.. skeletal muscle)), and / or fluid (e.g.., CSF and or serum) of the subject relative to baseline and / or relative to FXN activity in a cell, tissue, or fluid of an individual with a disorder associated with FXN deficiency who has not been administered the pharmaceutical composition or AAV particle.

[0062] In some embodiments, a method of deliver}’ or treatment provided herein further comprises administering to the subject at least one additional agent and / or therapy. In some embodiments, the at least one additional agent and / or therapy comprises an agent and / or therapy suitable for treating the disorder associated with FXN deficiency (e.g., Friedreich’s Ataxia). In some embodiments, the at least one additional agent and / or therapy comprises omaveloxolone or idebenone. In some embodiments, a method of deliver} or treatment provided herein further comprises administering an immunosuppressant to the subject. In some embodiments, the immunosuppressant comprises a corticosteroid (e.g., prednisone, prednisolone, methylprednisolone, and / or dexamethasone), rapamycin, mycophenolate mofetil, tacrolimus, rituximab, and / or eculizumab hydroxychloroquine.

[0063] In some aspects, the present disclosure provides a pharmaceutical composition or AAV particle provided herein for use in a method of treating a disorder provided herein.

[0064] In some aspects, the present disclosure provides a pharmaceutical composition or AAV particle provided herein for use in a method of treating a disorder is associated with FXN deficiency, or at least one symptom thereof, in a subject. In some embodiments, the disorder is Friedreich’s Ataxia. Insome embodiments, the subject has, has been diagnosed with having, or is at risk of having Friedreich’s Ataxia.

[0065] In some aspects, the present disclosure provides a use of a pharmaceutical composition or AAV particle provided herein in the manufacture of a medicament for the treatment of a disorder associated with FXN deficiency, or at least one symptom thereof, in a subject. In some embodiments, the disorder is Friedreich’s Ataxia. In some embodiments, the subject has, has been diagnosed with having, or is at risk of having Friedreich’s Ataxia.Enumerated Embodiments1. An adeno-associated virus (AAV) particle comprising a viral genome comprising a frataxin (FXN)- encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g.. an AAV9 capsid variant), wherein the AAV capsid variant comprises an amino acid sequence having the following formula: [N1]-[N2]-[N3] (SEQ ID NO: 4681). wherein [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682) and wherein:(i) [Nl] comprises amino acids Xi, X2, X3. and X4, wherein X4is Q. K, E, S. P, R, N, H; and / or(ii) [N3] comprises amino acids X5, X6, and X?, wherein X5is I, V, T, M, S, N, L, F.2. The AAV particle of embodiment 1, wherein the AAV capsid variant comprises the amino acid Q at position 585, as numbered according to SEQ ID NO: 138 or 981.3. The AAV particle of embodiment 1, wherein the AAV capsid variant comprises an amino acid other than Q at position 585, as numbered according to SEQ ID NO: 138 or 981.4. The AAV particle of embodiment 1 or 3, wherein the AAV capsid variant comprises the amino acid K at position 585, as numbered according to SEQ ID NO: 138 or 981.5. The AAV particle of any one of embodiments 1-4, wherein the AAV capsid variant comprises one, two, three, or all of:(i) an amino acid other than T at position 582 (e.g., S, R, A, I, C, N, K, L. or Q):(ii) an amino acid other than N at position 583 (e.g., T. G, V. S, Y, K. I. H, D. or F);(iii) an amino acid other than H at position 584 (e.g.. T, N, K, D, I, S. P, A, Y. E, V. L, M, R, Q, or C); and / or(iv) an amino acid other than Q at position 585 (e.g., K, E, S, P, R, N, or H); wherein the amino acids are numbered according to SEQ ID NO: 138.6. The AAV particle of any one of embodiments 1-5. wherein [Nl] comprises amino acids Xi, X2, X3, and X4, wherein X4is Q, K. E, S, P, R, N, or H.7. The AAV particle of embodiment 6, wherein X4 is Q or K.8. The AAV particle of any one of embodiment 7, wherein X4 is Q.9. The AAV particle of embodiment 7, wherein X4 is K.10. The AAV particle of any one of embodiments 1-9, wherein the AAV capsid variant comprises an amino acid other than H at position 584 (e.g., T), as numbered according to SEQ ID NO: 138.11. The AAV particle of any one of embodiments 1-10, wherein the AAV capsid variant comprises tire amino acid T at position 584, as numbered according to SEQ ID NO: 138 or 981.12. The AAV particle of any one of embodiments 1-11, wherein:(i) Xi is T, S. R, A. I. C, N, K. L, or Q;(ii) X2is N, T, G. V, S, Y, K, I, H. D, or F; and / or(iii) X3is T, N. K, D, I, S. P, A, Y, E, V. L, M. R, H, Q, or C.13. The AAV particle of any one of embodiments 1-12, wherein [Nl] comprises TN, NT, NK, SN, TT, RN, TG. TV, ST, TS, TY, AN, TK, TI, IN, TH, TD, CN. NN, KN, LN, SG, TF, RT, SY. SS, QN, ND, NP, GK, TA, VK, NY, TE, SK. NI, YN, GT, TL, TM, YT, TR. NS, IT, NA, KT, GN, HT, DT, NE, NH, YI, HN, NQ, FS, NM, NL, SM. NC, VT, KQ, TQ, DQ, IQ. SQ, PS. KE, AQ, YQ, TP, EQ. VQ, LQ, MQ, KS, IE, RQ, IK, AK, PK, NR, HQ, QQ, or CQ.14. The AAV particle of any one of embodiments 1-13, wherein [Nl] comprises TNT, TNK, TNN, SNN, SNK, SNT, TTN, TND, TTI, RNT, TTK, TTS, TTD, TNP, TTT, TGK, TTA, TVK, TNY, STK, TTE, TSK, TNI, TYN, STI, TTV, TGT, TTL, TTM, ANN, SNI, TKN, TYT, TTR, TNS, TST, TIT, INT, TNA, TKT, STN, ANT, RNN, TGN, TSN, THT, TDT, TNE, CNT, INN, NNN. KNN, LNN, TIN, TNH, STT, SNS, STS, TYI, SGT, THN, TNQ, RNI, TFS, RNS, TNM. RTT, KNT, TNL, TSM, SYT, TNC, SST, TVT, QNT, NTK, NNQ, NKQ, NNE, NTQ, NDQ, TIQ, TKQ, TSQ, TDQ, NPS, NKE, TTQ, GKQ, TAQ, VKQ. NYQ, NTP. TEQ, SKQ, NIQ, YNQ, TVQ, GTQ, NTR, TLQ, TMQ, KNQ. YTQ. NKS. NTE, NIE, TRQ, NSQ, YTK, NIK. NNK, NSK. ITK, NAK, KTK, GNQ. SNQ. HTK. DTK. NEQ. NPK. YTE, NNR, INQ, NHQ, YIQ, HNQ, ITQ, STQ. NSN. NQQ. NNP. ITE, NTN, FSQ, NNH, NMQ, NTS, NLQ. SMQ. NCQ, or VTQ15. The AAV particle of any one of embodiments 1-14, wherein [Nl] is or comprises TNTQ (SEQ ID NO: 4688), TNTK (SEQ ID NO: 4689), TNNQ (SEQ ID NO: 4690). SNNQ (SEQ ID NO: 4691), TNKQ(SEQ ID NO: 4692), TNNE (SEQ ID NO: 4693), SNKQ (SEQ ID NO: 4694), SNTQ (SEQ ID NO: 4695), TTNQ (SEQ ID NO: 4696), TNDQ (SEQ ID NO: 4697), TTIQ (SEQ ID NO: 4698), RNTQ (SEQ ID NO: 4699), TTKQ (SEQ ID NO: 4700), TTSQ (SEQ ID NO: 4701), TTDQ (SEQ ID NO: 4702), TNPS (SEQ ID NO: 4703), TNKE (SEQ ID NO: 4704), TTTQ (SEQ ID NO: 4705), TGKQ (SEQ ID NO: 4706), TTAQ (SEQ ID NO: 4707), TVKQ (SEQ ID NO: 4708), TNYQ (SEQ ID NO: 4709), TNTP (SEQ ID NO: 4710). STKQ (SEQ ID NO: 4711), TTEQ (SEQ ID NO: 4712). TSKQ (SEQ ID NO: 4713), TNIQ (SEQ ID NO: 4714), TYNQ (SEQ ID NO: 4715), STIQ (SEQ ID NO: 4716), TTVQ (SEQ ID NO: 4717), TGTQ (SEQ ID NO: 4718), TNTR (SEQ ID NO: 4719), TTLQ (SEQ ID NO: 4720), TTMQ (SEQ ID NO: 4721), ANNQ (SEQ ID NO: 4722), SNIQ (SEQ ID NO: 4723), TKNQ (SEQ ID NO: 4724), TYTQ (SEQ ID NO: 4725), TNKS (SEQ ID NO: 4726), SNTE (SEQ ID NO: 4727). TNTE (SEQ ID NO: 4728). TNIE (SEQ ID NO: 4729), TTRQ (SEQ ID NO: 4730), TNSQ (SEQ ID NO: 4731), TYTK (SEQ ID NO: 4732), TTTK (SEQ ID NO: 4733). TNIK (SEQ ID NO: 4734), SNTK (SEQ ID NO: 4735), TNNK (SEQ ID NO: 4736), TNSK (SEQ ID NO: 4737). TSTK (SEQ ID NO: 4738), TITK (SEQ ID NO: 4739), INTK (SEQ ID NO: 4740), TNAK (SEQ ID NO: 4741). TKTK (SEQ ID NO: 4742). STNQ (SEQ ID NO: 4743), ANTK (SEQ ID NO: 4744), RNNQ (SEQ ID NO: 4745). TGNQ (SEQ ID NO: 4746), TSNQ (SEQ ID NO: 4747), THTK (SEQ ID NO: 4748). TDTK (SEQ ID NO: 4749). TNEQ (SEQ ID NO: 4750), CNTQ (SEQ ID NO: 4751), TNPK (SEQ ID NO: 4752), INNQ (SEQ ID NO: 4753), TYTE (SEQ ID NO: 4754), NNNQ (SEQ ID NO: 4755), KNNQ (SEQ ID NO: 4756). TNNR (SEQ ID NO: 4757), LNNQ (SEQ ID NO: 4758). TINQ (SEQ ID NO: 4759), TNHQ (SEQ ID NO: 4760), STTQ (SEQ ID NO: 4761), SNSQ (SEQ ID NO: 4762), STSQ (SEQ ID NO: 4763), TYIQ (SEQ ID NO: 4764), SGTQ (SEQ ID NO: 4765), THNQ (SEQ ID NO: 4766), TITQ (SEQ ID NO: 4767), TSTQ (SEQ ID NO: 4768), TNSN (SEQ ID NO: 4769). TNQQ (SEQ ID NO: 4770), RNIQ (SEQ ID NO: 4771), TNNP (SEQ ID NO: 4772), TITE (SEQ ID NO: 4773), TNTN (SEQ ID NO: 4774), TFSQ (SEQ ID NO: 4775), RNSQ (SEQ ID NO: 4776), INTQ (SEQ ID NO: 4777), RNTE (SEQ ID NO: 4778), TNNH (SEQ ID NO: 4779), TNMQ (SEQ ID NO: 4780), RTTQ (SEQ ID NO: 4781), SNIE (SEQ ID NO: 4782), TNTS (SEQ ID NO: 4783), KNTQ (SEQ ID NO: 4784), TNLQ (SEQ ID NO: 4785), TSMQ (SEQ ID NO: 4786), SYTQ (SEQ ID NO: 4787), TNCQ (SEQ ID NO: 4788), SSTQ (SEQ ID NO: 4789). TVTQ (SEQ ID NO: 4790), or QNTQ (SEQ ID NO: 4791).16. The AAV particle of embodiment 15, wherein [Nl] is or comprises TNTQ (SEQ ID NO: 4688).17. The AAV particle of embodiment 15, wherein [Nl] is or comprises TNTK (SEQ ID NO: 4689).18. The AAV particle of any one of embodiments 1-17, wherein [N1]-[N2] comprises:(i) TQDWHR (SEQ ID NO: 4686). TKDWHR (SEQ ID NO: 4792), NQDWHR (SEQ ID NO: 4793), KQDWHR (SEQ ID NO: 4794). NEDWHR (SEQ ID NO: 4795), DQDWHR (SEQ ID NO: 4796), IQDWHR (SEQ ID NO: 4797), SQDWHR (SEQ ID NO: 4798), PSDWHR (SEQ ID NO: 4799),KEDWHR (SEQ ID NO: 4800), AQDWHR (SEQ ID NO: 4801), YQDWHR (SEQ ID NO: 4802), TPDWHR (SEQ ID NO: 4803), EQDWHR (SEQ ID NO: 4804), VQDWHR (SEQ ID NO: 4805), TRDWHR (SEQ ID NO: 4806), LQDWHR (SEQ ID NO: 4807), MQDWHR (SEQ ID NO: 4808), KSDWHR (SEQ ID NO: 4809), TEDWHR (SEQ ID NO: 4810), IEDWHR (SEQ ID NO: 4811), RQDWHR (SEQ ID NO: 4812), IKDWHR (SEQ ID NO: 4813), NKDWHR (SEQ ID NO: 4814), SKDWHR (SEQ ID NO: 4815), AKDWHR (SEQ ID NO: 4816), PKDWHR (SEQ ID NO: 4817), NRDWHR (SEQ ID NO: 4818), HQDWHR (SEQ ID NO: 4819), SNDWHR (SEQ ID NO: 4820). QQDWHR (SEQ ID NO: 4821), NPDWHR (SEQ ID NO: 4822), TNDWHR (SEQ ID NO: 4823), NHDWHR (SEQ ID NO: 4824), TSDWHR (SEQ ID NO: 4825), or CQDWHR (SEQ ID NO: 4826);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3. 4, or 5 amino acids, e.g.. consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).19. The AAV particle of any one of embodiments 1-18, wherein [N1]-[N2] comprises:(i) NTQDWHR (SEQ ID NO: 4827), NTKDWHR (SEQ ID NO: 4828). NNQDWHR (SEQ ID NO: 4829), NKQDWHR (SEQ ID NO: 4830). NNEDWHR (SEQ ID NO: 4831), TNQDWHR (SEQ ID NO: 4832), NDQDWHR (SEQ ID NO: 4833). TIQDWHR (SEQ ID NO: 4834). TKQDWHR (SEQ ID NO: 4835), TSQDWHR (SEQ ID NO: 4836), TDQDWHR (SEQ ID NO: 4837), NPSDWHR (SEQ ID NO: 4838), NKEDWHR (SEQ ID NO: 4839), TTQDWHR (SEQ ID NO: 4840), GKQDWHR (SEQ ID NO: 4841), TAQDWHR (SEQ ID NO: 4842), VKQDWHR (SEQ ID NO: 4843), NYQDWHR (SEQ ID NO: 4844), NTPDWHR (SEQ ID NO: 4845), TEQDWHR (SEQ ID NO: 4846), SKQDWHR (SEQ ID NO: 4847), NIQDWHR (SEQ ID NO: 4848), YNQDWHR (SEQ ID NO: 4849), TVQDWHR (SEQ ID NO: 4850), GTQDWHR (SEQ ID NO: 4851), NTRDWHR (SEQ ID NO: 4852), TLQDWHR (SEQ ID NO: 4853), TMQDWHR (SEQ ID NO: 4854), KNQDWHR (SEQ ID NO: 4855), YTQDWHR (SEQ ID NO: 4856), NKSDWHR (SEQ ID NO: 4857), NTEDWHR (SEQ ID NO: 4858), NIEDWHR (SEQ ID NO: 4859), TRQDWHR (SEQ ID NO: 4860), NSQDWHR (SEQ ID NO: 4861), YTKDWHR (SEQ ID NO: 4862), TTKDWHR (SEQ ID NO: 4863), NIKDWHR (SEQ ID NO: 4864). NNKDWHR (SEQ ID NO: 4865), NSKDWHR (SEQ ID NO: 4866). STKDWHR (SEQ ID NO: 4867), ITKDWHR (SEQ ID NO: 4868), NAKDWHR (SEQ ID NO: 4869), KTKDWHR (SEQ ID NO: 4870), GNQDWHR (SEQ ID NO: 4871), SNQDWHR (SEQ ID NO: 4872). HTKDWHR (SEQ ID NO: 4873), DTKDWHR (SEQ ID NO: 4874), NEQDWHR (SEQ ID NO: 4875). NPKDWHR (SEQ ID NO: 4876), YTEDWHR (SEQ ID NO: 4877), NNRDWHR (SEQ ID NO: 4878), INQDWHR (SEQ ID NO: 4879), NHQDWHR (SEQ ID NO: 4880), YIQDWHR (SEQ ID NO: 4881). HNQDWHR (SEQ ID NO: 4882), ITQDWHR (SEQ ID NO: 4883), STQDWHR (SEQ ID NO: 4884). NSNDWHR (SEQ ID NO: 4885), NQQDWHR (SEQ IDNO: 4886), NNPDWHR (SEQ ID NO: 4887), ITEDWHR (SEQ ID NO: 4888), NTNDWHR (SEQ ID NO: 4889), FSQDWHR (SEQ ID NO: 4890), NNHDWHR (SEQ ID NO: 4891), NMQDWHR (SEQ ID NO: 4892), NTSDWHR (SEQ ID NO: 4893), NLQDWHR (SEQ ID NO: 4894), SMQDWHR (SEQ ID NO: 4895), NCQDWHR (SEQ ID NO: 4896), or VTQDWHR (SEQ ID NO: 4897);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3. 4, 5, or 6 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).20. The AAV particle of any one of embodiments 1-19, wherein [N1]-[N2] is or comprises:(i) TNTQDWHR (SEQ ID NO: 4898), TNTKDWHR (SEQ ID NO: 4899), TNNQDWHR (SEQ ID NO: 4900), SNNQDWHR (SEQ ID NO: 4901), TNKQDWHR (SEQ ID NO: 4902), TNNEDWHR (SEQ ID NO: 4903), SNKQDWHR (SEQ ID NO: 4904). SNTQDWHR (SEQ ID NO: 4905). TTNQDWHR (SEQ ID NO: 4906), TNDQDWHR (SEQ ID NO: 4907). TTIQDWHR (SEQ ID NO: 4908). RNTQDWHR (SEQ ID NO: 4909), TTKQDWHR (SEQ ID NO: 4910), TTSQDWHR (SEQ ID NO: 4911), TTDQDWHR (SEQ ID NO: 4912), TNPSDWHR (SEQ ID NO: 4913), TNKEDWHR (SEQ ID NO: 4914), TTTQDWHR (SEQ ID NO: 4915). TGKQDWHR (SEQ ID NO: 4916), TTAQDWHR (SEQ ID NO: 4917), TVKQDWHR (SEQ ID NO: 4918), TNYQDWHR (SEQ ID NO: 4919), TNTPDWHR (SEQ ID NO: 4920), STKQDWHR (SEQ ID NO: 4921), TTEQDWHR (SEQ ID NO: 4922), TSKQDWHR (SEQ ID NO: 4923), TNIQDWHR (SEQ ID NO: 4924), TYNQDWHR (SEQ ID NO: 4925), STIQDWHR (SEQ ID NO: 4926), TTVQDWHR (SEQ ID NO: 4927), TGTQDWHR (SEQ ID NO: 4928), TNTRDWHR (SEQ ID NO: 4929), TTLQDWHR (SEQ ID NO: 4930), TTMQDWHR (SEQ ID NO: 4931), ANNQDWHR (SEQ ID NO: 4932), SNIQDWHR (SEQ ID NO: 4933), TKNQDWHR (SEQ ID NO: 4934), TYTQDWHR (SEQ ID NO: 4935), TNKSDWHR (SEQ ID NO: 4936), SNTEDWHR (SEQ ID NO: 4937), TNTEDWHR (SEQ ID NO: 4938), TNIEDWHR (SEQ ID NO: 4939), TTRQDWHR (SEQ ID NO: 4940), TNSQDWHR (SEQ ID NO: 4941), TYTKDWHR (SEQ ID NO: 4942), TTTKDWHR (SEQ ID NO: 4943), TNIKDWHR (SEQ ID NO: 4944), SNTKDWHR (SEQ ID NO: 4945). TNNKDWHR (SEQ ID NO: 4946), TNSKDWHR (SEQ ID NO: 4947), TSTKDWHR (SEQ ID NO: 4948), TITKDWHR (SEQ ID NO: 4949), INTKDWHR (SEQ ID NO: 4950), TNAKDWHR (SEQ ID NO: 4951), TKTKDWHR (SEQ ID NO: 4952), STNQDWHR (SEQ ID NO: 4953), ANTKDWHR (SEQ ID NO: 4954). RNNQDWHR (SEQ ID NO: 4955), TGNQDWHR (SEQ ID NO: 4956). TSNQDWHR (SEQ ID NO: 4957), THTKDWHR (SEQ ID NO: 4958), TDTKDWHR (SEQ ID NO: 4959), TNEQDWHR (SEQ ID NO: 4960), CNTQDWHR (SEQ ID NO: 4961), TNPKDWHR (SEQ ID NO: 4962), INNQDWHR (SEQ ID NO: 4963), TYTEDWHR (SEQ ID NO: 4964), NNNQDWHR (SEQ ID NO: 4965). KNNQDWHR (SEQ ID NO: 4966), TNNRDWHR(SEQ ID NO: 4967), LNNQDWHR (SEQ ID NO: 4968), TINQDWHR (SEQ ID NO: 4969), TNHQDWHR (SEQ ID NO: 4970), STTQDWHR (SEQ ID NO: 4971), SNSQDWHR (SEQ ID NO: 4972), STSQDWHR (SEQ ID NO: 4973), TYIQDWHR (SEQ ID NO: 4974), SGTQDWHR (SEQ ID NO: 4975), THNQDWHR (SEQ ID NO: 4976), TITQDWHR (SEQ ID NO: 4977), TSTQDWHR (SEQ ID NO: 4978), TNSNDWHR (SEQ ID NO: 4979), TNQQDWHR (SEQ ID NO: 4980), RNIQDWHR (SEQ ID NO: 4981). TNNPDWHR (SEQ ID NO: 4982), TITEDWHR (SEQ ID NO: 4983), TNTNDWHR (SEQ ID NO: 4984), TFSQDWHR (SEQ ID NO: 4985). RNSQDWHR (SEQ ID NO: 4986), INTQDWHR (SEQ ID NO: 4987), RNTEDWHR (SEQ ID NO: 4988), TNNHDWHR (SEQ ID NO: 4989), TNMQDWHR (SEQ ID NO: 4990), RTTQDWHR (SEQ ID NO: 4991), SNIEDWHR (SEQ ID NO: 4992), TNTSDWHR (SEQ ID NO: 4993), KNTQDWHR (SEQ ID NO: 4994), TNLQDWHR (SEQ ID NO: 4995). TSMQDWHR (SEQ ID NO: 4996), SYTQDWHR (SEQ ID NO: 4997), TNCQDWHR (SEQ ID NO: 4998), SSTQDWHR (SEQ ID NO: 4999), TVTQDWHR (SEQ ID NO: 5000), or QNTQDWHR (SEQ ID NO: 5001);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3, 4. 5. 6, or 7 amino acids, e.g.. consecutive amino acids, thereof;(iii) an amino acid sequence comprising one. two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one. two, or three but no more than four substitutions, relative to any one of the amino acid sequences in (i).21. The AAV particle of embodiment 20, wherein [N1]-[N2] is or comprises TNTQDWHR (SEQ ID NO: 4898).22. The AAV particle of embodiment 20, wherein [N1]-[N2] is or comprises TNTKDWHR (SEQ ID NO: 4899).23. The AAV particle of any one of embodiments 1-22, wherein the AAV capsid variant comprises one, tw o. or all of: an amino acid other than Q at position 590 (e.g., I, V, T, M, S, N, L, or F), an amino acid other than A at position 591 (e.g., Y, P, N, S, T, G, E, V. W, F, Q), and / or an amino acid other than Q at position 592 (e.g., G, N, K. H, R, E, L, P, or M), as numbered according to SEQ ID NO: 138 or 981.24. The AAV particle of any one of embodiments 1-23, wherein the AAV capsid variant comprises an amino acid other than Q at position 590 (e.g., I, V. T, M. S, N, L. or F). as numbered according to SEQ ID NO: 138 or 981.25. The AAV particle of any one of embodiments 1-24, wherein the AAV capsid variant comprises tire amino acid I at position 590. as numbered according to SEQ ID NO: 138 or 981.26. The AAV particle of any one of embodiments 1-24, wherein the AAV capsid variant comprises the amino acid V at position 590, as numbered according to SEQ ID NO: 138 or 981.27. The AAV particle of any one of embodiments 1-26, wherein the AAV capsid variant comprises the amino acid A at position 591 and / or the amino acid Q at position 592, as numbered according to SEQ ID NO: 138 or 981.28. The AAV particle of any one of embodiments 1-27, wherein [N3] comprises amino acids X5. X6. and X?, wherein Xs is I, V. T, M. S. N, L. or F.29. The AAV particle of any one of embodiments 1-28, wherein Xs is I or V.30. The AAV particle of embodiment 29, wherein X5 is I.31. The AAV particle of any one of embodiments 1-30, wherein:(i) X6is A. Y, P, N. S, T, G. E, V. W, F, or Q; and / or(ii) X7is Q, G, N, K, H. R, E, L. P, or M.32. The AAV particle of any one of embodiments 1-31, wherein [N3] comprises IA, IY, VP, IN, VN. VY. VA, IS, IT, TA, MA, SA, IG, IE. IV, NA, LA, IP, FA. VS, VT, IW, IF, IQ, VQ, AQ, AG, YQ, PQ, AN. NQ, SG, SQ, TQ, GQ. EQ, AK, AH, AR. AE, AL, AP, TM, SM, WQ, FQ, QQ, FM, AM, or SN.33. The AAV particle of any one of embodiments 1-32, wherein [N3] is or comprises IAQ, IAG, IYQ, VPQ, IAN, INQ, VNQ, VYQ, VAN, ISG, ISQ, VAQ, ITQ, TAQ, MAQ, SAQ, IGQ, IEQ, IVQ, NAQ, LAQ, IAK, IAH, IPQ, IAR, IAE, IAL, IAP, FAQ, VSQ, VTM, ISM, IWQ, IFQ, IQQ, VQQ, IFM, IAM, or ISN.34. The AAV particle of any one of embodiments 1-33, wherein [N3] is or comprises IAQ.35. The AAV particle of any one of embodiments 1-34, wherein [N2]-[N3] comprises:(i) DWHRIA (SEQ ID NO: 5002), DWHRIY (SEQ ID NO: 5003), DWHRVP (SEQ ID NO: 5004), DWHRIN (SEQ ID NO: 5005), DWHRVN (SEQ ID NO: 5006), DWHRVY (SEQ ID NO: 5007), DWHRVA (SEQ ID NO: 5008), DWHRIS (SEQ ID NO: 5009), DWHRIT (SEQ ID NO: 5010). DWHRTA (SEQ ID NO: 5011), DWHRMA (SEQ ID NO: 5012), DWHRSA (SEQ ID NO: 5013). DWHRIG (SEQ ID NO: 5014), DWHRIE (SEQ ID NO: 5015), DWHRIV (SEQ ID NO: 5016), DWHRNA (SEQ ID NO: 5017), DWHRLA (SEQ ID NO: 5018), DWHRIP (SEQ ID NO: 5019),DWHRFA (SEQ ID NO: 5020), DWHRVS (SEQ ID NO: 5021), DWHRVT (SEQ ID NO: 5022), DWHRIW (SEQ ID NO: 5023), DWHRIF (SEQ ID NO: 5024), DWHRIQ (SEQ ID NO: 5025), or DWHRVQ (SEQ ID NO: 5026);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3. 4, or 5 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).36. The AAV particle of any one of embodiments 1-35, wherein [N2]-[N3] is or comprises:(i) DWHRIAQ (SEQ ID NO: 5027), DWHR1AG (SEQ ID NO: 5028), DWHR1YQ (SEQ ID NO: 5029), DWHRVPQ (SEQ ID NO: 5030). DWHRIAN (SEQ ID NO: 5031), DWHRINQ (SEQ ID NO: 5032), DWHRVNQ (SEQ ID NO: 5033), DWHRVYQ (SEQ ID NO: 5034), DWHRVAN (SEQ ID NO: 5035), DWHRISG (SEQ ID NO: 5036), DWHRISQ (SEQ ID NO: 5037), DWHRVAQ (SEQ ID NO: 5038), DWHRITQ (SEQ ID NO: 5039), DWHRTAQ (SEQ ID NO: 5040), DWHRMAQ (SEQ ID NO: 5041), DWHRSAQ (SEQ ID NO: 5042), DWHRIGQ (SEQ ID NO: 5043). DWHRIEQ (SEQ ID NO: 5044), DWHRIVQ (SEQ ID NO: 5045), DWHRNAQ (SEQ ID NO: 5046), DWHRLAQ (SEQ ID NO: 5047), DWHRIAK (SEQ ID NO: 5048), DWHRIAH (SEQ ID NO: 5049), DWHRIPQ (SEQ ID NO: 5050), DWHRIAR (SEQ ID NO: 5051), DWHRIAE (SEQ ID NO: 5052), DWHRIAL (SEQ ID NO: 5053), DWHRIAP (SEQ ID NO: 5054), DWHRFAQ (SEQ ID NO: 5055), DWHRVSQ (SEQ ID NO: 5056), DWHRVTM (SEQ ID NO: 5057), DWHRISM (SEQ ID NO: 5058), DWHRIWQ (SEQ ID NO: 5059), DWHRIFQ (SEQ ID NO: 5060), DWHRIQQ (SEQ ID NO: 5061), DWHRVQQ (SEQ ID NO: 5062), DWHRIFM (SEQ ID NO: 5063), DWHRIAM (SEQ ID NO: 5064), or DWHRISN (SEQ ID NO: 5065);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3, 4, 5, or 6 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).37. The AAV particle of any one of embodiments 1-36, wherein [N2]-[N3] is or comprises DWHRIAQ (SEQ ID NO: 5027).38. The AAV particle of any one of embodiments 1-37, wherein [N1]-[N2]-[N3] is or comprises:(i) the amino acid sequence of any one of SEQ ID NOs: 343-538:(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).39. The AAV particle of embodiment 38, wherein [N1]-[N2]-[N3] is or comprises TNTQDWHRIAQ (SEQ ID NO: 343).40. The AAV particle of embodiment 38, wherein [N1]-[N2]-[N3] is or comprises TNTKDWHRIAQ (SEQ ID NO: 344).41. The AAV particle of any one of embodiments 1-40, wherein the AAV capsid variant comprises one, two. three, or all of: an amino acid other than T at position 593 (e.g., S, N. P, A, or I), an amino acid other than G at position 594 (e.g.. N, D, R. V, A. S, or Q), an amino acid other than W at position 595 (e.g., S, C. R, L, or G), and / or an amino acid other than V at position 596 (e.g., A, S. I. C, G, D, F, L, or T), as numbered according to SEQ ID NO: 138 or 981.42. The AAV particle of any one of embodiments 1-40, wherein the AAV capsid variant comprises the amino acid T at position 593, the amino acid G at position 594, the amino acid W at position 595, and the amino acid V at position 596. as numbered according to SEQ ID NO: 138 or 981.43. The AAV particle of any one of embodiments 1-42, wherein the AAV capsid variant further comprises [N4], wherein [N4] comprises amino acids Xg, X9, X10, and X1, wherein:(i) X8is T, S, N, P, A, or I;(ii) X9is G, N, D, R, V, A, S, or Q;(iii) X10 is W, S, C. R, L, or G; and / or(iv) Xu is V, A, S, I, C, G, D, F, L, or T.44. The AAV particle of embodiment 43, wherein [N4] comprises TG, TN, SN, NN, SG, PG, TD, AG, IG, NG. TR, TV, TA, TS, SV, TQ, WV, WA, WS, WI, WC, WG, CV, RV, LV. GV, WD, WF, WL, WT, GW, NW. GS, DW, GC. GR, GL, GG, RW, VW, AW, SW, or QW.45. The AAV particle of embodiment 43 or 44, wherein [N4] comprises TGW, TNW. SNW. NNW, SGW, PGW, TGS, TDW, TGC, TGR, TGL, TGG, AGW, IGW, NGW. TRW, TVW, TAW. TSW. SVW,TQW, GWV, GW A, NWS, NWV, NWI, GWS, GWI, GWC, GWG, GSV, DWV, GCV, GRV, GLV, GGV, GWD, GWF, RWV, VWV, GWL, AWV, SWV, GWT, or QWV.46. The AAV particle of any one of embodiments 43-45. wherein [N4] is or comprises TGWV (SEQ ID NO: 5066), TGWA (SEQ ID NO: 5067), TNWS (SEQ ID NO: 5068), SNWV (SEQ ID NO: 5069), TNWV (SEQ ID NO: 5070), TNWI (SEQ ID NO: 5071), NNWV (SEQ ID NO: 5072), TGWS (SEQ ID NO: 5073), TGWI (SEQ ID NO: 5074), TGWC (SEQ ID NO: 5075). TGWG (SEQ ID NO: 5076). SGWV (SEQ ID NO: 5077), PGWV (SEQ ID NO: 5078), TGSV (SEQ ID NO: 5079), TDWV (SEQ ID NO: 5080), TGCV (SEQ ID NO: 5081), TGRV (SEQ ID NO: 5082). TGLV (SEQ ID NO: 5083), TGGV (SEQ ID NO: 5084). AGWV (SEQ ID NO: 5085), IGWV (SEQ ID NO: 5086). TGWD (SEQ ID NO: 5087), NGWV (SEQ ID NO: 5088), TGWF (SEQ ID NO: 5089), TRWV (SEQ ID NO: 5090), TVWV (SEQ ID NO: 5091). TGWL (SEQ ID NO: 5092). TAWV (SEQ ID NO: 5093). TSWV (SEQ ID NO: 5094), TGWT (SEQ ID NO: 5095). SVWV (SEQ ID NO: 5096). TQWV (SEQ ID NO: 5097). or PGWG (SEQ ID NO: 5098).47. The AAV particle of any one of embodiments 43-46, wherein [N4] is or comprises TGWV (SEQ ID NO: 5066).48. The AAV particle of any one of embodiments 43-47, wherein [N1]-[N2]-[N3]-[N4] is or comprises:(i) the amino acid sequence of any one of SEQ ID NOs: 201-245, 247-250, 253-255, 257-265, 268-274, 276-286, 288, 290-297, 299-303, 305-309, 311, 313-319, 323-328, 330-337, 339-342, 539-542, 544, 546, 547, 549-557, 559-589, 592, 593, 595. 596, 598, 599, 601-608, 610-614, 616-622, 625, 628, 630, 631, 633, 636, 638, 639-646, 649, 651-657. 667, 669, 670, 672, 673, 679-683, 685-690, 692, 693, 695, 697, 699-701. 703-705, 708-710, 712-717, 719-723, 728-731, 733-738, 740, and 742;(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), c.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).49. The AAV particle of embodiment 48, wherein [N1]-[N2]-[N3]-[N4] is or comprises TNTQDWHRIAQTGWV (SEQ ID NO: 201).50. The AAV particle of any one of embodiment 48. wherein [N 1 ]-[N2] -|N3]-[N4] is or comprises TNTKDWHRIAQTGWV (SEQ ID NO: 202).51. An AAV particle comprising a viral genome comprising a frataxin (FXN)-encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising an amino acid sequence having the following formula: [N1]-[N2]-[N3] (SEQ ID NO: 4683), wherein [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682) and wherein:(i) [Nl] comprises amino acids Xi, X2, X3, and X4. wherein X4 is Q, P, or a conservative substitution thereof; and / or(ii) [N3] comprises amino acids X5, X6, and X7, wherein X5is I, V, or a conservative substitution thereof.52. The AAV particle of embodiment 51, wherein the AAV capsid variant comprises the amino acid Q at position 585, as numbered according to SEQ ID NO: 138 or 981.53. The AAV particle of embodiment 51 or 52, wherein the AAV capsid variant comprises one, two. three, or all of:(i) an amino acid other than T at position 582 (e.g.. S);(ii) an amino acid other than N at position 583 (e.g., T, G. S, I, or V);(iii) an amino acid other than H at position 584 (e.g., N, I, S, A. V, or L); and / or(iv) an amino acid other than Q at position 585 (e g., P), wherein the amino acids are as numbered according to SEQ ID NO: 138 or 981.54. The AAV particle of any one of embodiments 51-53, wherein [Nl] comprises amino acids Xi, X2, X3, and X4, wherein X4is Q or P.55. The AAV particle of any one of embodiments 51-54, wherein X4 is Q.56. The AAV particle of any one of embodiments 51-55, wherein the AAV capsid variant comprises an amino acid other than H at position 584 (e.g., T), as numbered according to SEQ ID NO: 138 or 981.57. The AAV particle of any one of embodiments 51-56, wherein the AAV capsid variant comprises the amino acid T at position 584. as numbered according to SEQ ID NO: 138 or 981.58. The AAV particle of any one of embodiments 51-57, wherein:(i) Xi is T or S;(ii) X2is N, T. G, S, I, or V; and / or(iii) X3is T. N, 1, S, A. V, or L.59. The AAV particle of any one of embodiments 51-58. wherein [Nl] comprises TN, TT, TG, ST, TS, TI, TV, TQ, NQ, IQ, SQ, AQ, VQ, TP, LQ, NT. TA, NI, GT, IT, NN, TL, NS, or VT.60. The AAV particle of any one of embodiments 51-59, wherein [Nl] comprises TNT, TTN, TTI, TTS, TTT, TTA, TNI, TTV, TGT, STT, TST, TIT, TNN, TTL, TNS, TVT, NTQ, TNQ, TIQ, TSQ, TTQ, TAQ, NIQ, TVQ, GTQ, STQ, ITQ. NTP, NNQ. TLQ, NSQ, or VTQ.61. The AAV particle of any one of embodiments 51-60. wherein [Nl] is or comprises TNTQ (SEQ ID NO: 4688), TTNQ (SEQ ID NO: 4696), TTIQ (SEQ ID NO: 4698), TTSQ (SEQ ID NO: 4701), TTTQ (SEQ ID NO: 4705). TTAQ (SEQ ID NO: 4707), TNIQ (SEQ ID NO: 4714). TTVQ (SEQ ID NO: 4717), TGTQ (SEQ ID NO: 4718). STTQ (SEQ ID NO: 4761), TSTQ (SEQ ID NO: 4768), TITQ (SEQ ID NO: 4767), TNTP (SEQ ID NO: 4710), TNNQ (SEQ ID NO: 4690), TTLQ (SEQ ID NO: 4720), TNSQ (SEQ ID NO: 4731), or TVTQ (SEQ ID NO: 4790).62. The AAV particle of embodiment 61, wherein [Nl] is or comprises TNTQ (SEQ ID NO: 4688).63. The AAV particle of any one of embodiments 51-62, wherein [N1]-[N2] comprises:(i) TQDWHR (SEQ ID NO: 4686), NQDWHR (SEQ ID NO: 4793), IQDWHR (SEQ ID NO: 4797). SQDWHR (SEQ ID NO: 4798), AQDWHR (SEQ ID NO: 4801), VQDWHR (SEQ ID NO: 4805). TPDWHR (SEQ ID NO: 4803), or LQDWHR (SEQ ID NO: 4807);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i). e.g., any 2, 3, 4, or 5 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).64. The AAV particle of any one of embodiments 51-63, wherein [N1]-[N2] comprises:(i) NTQDWHR (SEQ ID NO: 4827), TNQDWHR (SEQ ID NO: 4832), TIQDWHR (SEQ ID NO: 4834), TSQDWHR (SEQ ID NO: 4836), TTQDWHR (SEQ ID NO: 4840), TAQDWHR (SEQ ID NO: 4842), NIQDWHR (SEQ ID NO: 4848), TVQDWHR (SEQ ID NO: 4850), GTQDWHR (SEQ ID NO: 4851), STQDWHR (SEQ ID NO: 4884), ITQDWHR (SEQ ID NO: 4883). NTPDWHR (SEQ ID NO: 4845), NNQDWHR (SEQ ID NO: 4829), TLQDWHR (SEQ ID NO: 4853), NSQDWHR (SEQ ID NO: 4861), VTQDWHR (SEQ ID NO: 4897);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3. 4, 5 or 6 amino acids, e.g.. consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).65. The AAV particle of any one of embodiments 51 -64, wherein [N 1 ] - [N2] is or comprises :(i) TNTQDWHR (SEQ ID NO: 4898), TTNQDWHR (SEQ ID NO: 4906), TTIQDWHR (SEQ ID NO: 4908), TTSQDWHR (SEQ ID NO: 4911), TTTQDWHR (SEQ ID NO: 4915), TTAQDWHR (SEQ ID NO: 4917). TNIQDWHR (SEQ ID NO: 4924). TTVQDWHR (SEQ ID NO: 4927), TGTQDWHR (SEQ ID NO: 4928), STTQDWHR (SEQ ID NO: 4971), TSTQDWHR (SEQ ID NO: 4978), TITQDWHR (SEQ ID NO: 4977). TNTPDWHR (SEQ ID NO: 4920). TNNQDWHR (SEQ ID NO: 4900), TTLQDWHR (SEQ ID NO: 4930), TNSQDWHR (SEQ ID NO: 4941). TVTQDWHR (SEQ ID NO: 5000);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3, 4. 5 6. or 7 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one. two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one. two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).66. The AAV particle of embodiment 65, wherein [N1]-[N2] is or comprises TNTQDWHR (SEQ ID NO: 4898).67. The AAV particle of any one of embodiments 51-66, wherein the AAV capsid variant comprises one, two. or all of: an amino acid other than Q at position 590 (e.g., I or V), an amino acid other than A at position 591 (e.g., P, S, Y, or N), and / or an amino acid other than Q at position 592 (e.g., G or N), as numbered according to SEQ ID NO: 138 or 981.68. The AAV particle of any one of embodiments 51-67, wherein the AAV capsid variant comprises an amino acid other than Q at position 590 (e.g., I or V), as numbered according to SEQ ID NO: 138 or 981.69. The AAV particle of any one of embodiments 51-68, wherein the AAV capsid variant comprises the amino acid I at position 590, as numbered according to SEQ ID NO: 138 or 981.70. The AAV particle of any one of embodiments 51-68, wherein the AAV capsid variant comprises the amino acid V at position 590, as numbered according to SEQ ID NO: 138 or 981.71. The AAV particle of any one of embodiments 51-70, wherein the AAV capsid variant comprises the amino acid A at position 591 and / or the amino acid Q at position 592, as numbered according to SEQ ID NO: 138 or 981.72. The AAV particle of any one of embodiments 51-71. wherein [N3] comprises amino acids X,, Xe, and X7, wherein X5is I or V.73. The AAV particle of embodiment 72, wherein Xs is I.74. The AAV particle of any one of embodiments 51-73, wherein:(i) X6is A, P, S, Y, or N; and / or(ii) X7is Q, G. or N.75. The AAV particle of any one of embodiments 51-74, wherein [N3] comprises IA, VP, VA, VS, IY, IN, IS. AQ, AG, PQ, SQ. AN. YQ, or NQ.76. The AAV particle of any one of embodiments 51-75, wherein [N3] is or comprises IAQ, IAG, VPQ, VAQ, VSQ, IAN, IYQ, INQ, or ISQ.77. The AAV particle of any one of embodiments 51-76, wherein [N3] is or comprises IAQ.78. The AAV particle of any one of embodiments 51-77, wherein [N2]-[N3] comprises:(i) DWHRIA (SEQ ID NO: 5002), DWHRVP (SEQ ID NO: 5004), DWHRVA (SEQ ID NO: 5008), DWHRVS (SEQ ID NO: 5021), DWHRIY (SEQ ID NO: 5003). DWHRIN (SEQ ID NO: 5005), or DWHRIS (SEQ ID NO: 5009);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3, 4, or 5 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).79. The AAV particle of any one of embodiments 51-78, wherein [N2]-[N3] is or comprises:(i) DWHRIAQ (SEQ ID NO: 5027), DWHRIAG (SEQ ID NO: 5028), DWHRVPQ (SEQ ID NO: 5030), DWHRVAQ (SEQ ID NO: 5038), DWHRVSQ (SEQ ID NO: 5056), DWHRIAN (SEQ ID NO: 5031), DWHRIYQ (SEQ ID NO: 5029). DWHRINQ (SEQ ID NO: 5032). or DWHRISQ (SEQ ID NO: 5037);(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3, 4, 5, or 6 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).80. The AAV particle of any one of embodiments 51-79, wherein [N2]-[N3] is or comprises DWHRIAQ (SEQ ID NO: 5027).81. The AAV particle of any one of embodiments 51-80, wherein [N1]-[N2]-[N3] is or comprises:(i) the amino acid sequence of any one of SEQ ID NOs: 343. 350, 352, 355. 359, 361, 364. 367, 370, 371, 373. 374, 376. 377. 378, 381. 395, 420, 454. 457, 460, 464. 481, 482. 488, 493, 494. 516, 525, 536;(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i). e.g.. any 2, 3, 4. 5. 6, 7, 8, 9. or 10 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one. two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one. two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).82. The AAV particle of any one of embodiments 51-81, wherein [N1]-[N2]-[N3] is or comprises TNTQDWHRIAQ (SEQ ID NO: 343).83. The AAV particle of any one of embodiments 51-82, wherein the AAV capsid variant comprises the amino acid W at position 595, as numbered according to SEQ ID NO: 138 or 981.84. The AAV particle of any one of embodiments 51-83, wherein the AAV capsid variant comprises one. two or all of: an amino acid other than T (e.g.. S or N) at position 593, an amino acid other than G (e g., N) a position 594, and / or an amino acid other than V (e.g., A, I, or S) at position 596, as numbered according to SEQ ID NO: 138 or 981.85. The AAV particle of any one of embodiments 51-84, wherein the AAV capsid variant comprises:(i) the amino acid T at position 593, the amino acid G at position 594, the amino acid W at position 595, and the amino acid V at position 596, as numbered according to SEQ ID NO: 138 or 981:(ii) the amino acid T at position 593, the amino acid G at position 594, the amino acid W at position 595, and the amino acid A at position 596, as numbered according to SEQ ID NO: 138 or 981:(iii) the amino acid S at position 593, the amino acid N at position 594, the amino acid W at position 595, and the amino acid V at position 596, as numbered according to SEQ ID NO: 138 or 981;(iv) the amino acid N at position 593, die amino acid N at position 594, the amino acid W at position 595, and die amino acid V at position 596, as numbered according to SEQ ID NO: 138 or 981:(v) the amino acid T at position 593, die amino acid G at position 594, the amino acid W at position 595, and the amino acid I at position 596, as numbered according to SEQ ID NO: 138 or 981; or(vi) the amino acid T at position 593, the amino acid G at position 594, the amino acid W at position 595, and the amino acid S at position 596, as numbered according to SEQ ID NO: 138 or 981.86. The AAV particle of any one of embodiments 51-85, wherein the AAV capsid variant comprises the amino acid T at position 593. the amino acid G at position 594, the amino acid W at position 595, and the amino acid V at position 596, as numbered according to SEQ ID NO: 138 or 981.87. The AAV particle of any one of embodiments 51-86, wherein the AAV capsid variant further comprises [N4], wherein [N4] comprises amino acids X8. X9. Xio. and Xu, wherein X10 s W.88. The AAV particle of embodiment 87, wherein:(i) X8is T, S. or N;(ii) X9is G or N; and / or(iv) Xu is V. A, I, or S.89. The AAV particle of embodiment 87 or 88, wherein [N4] comprises TG, SN, NN, WV, WA, WI, WS, GW, or NW.90. The AAV particle of any one of embodiments 87-89, wherein [N4] comprises TGW, SNW, NNW, GWV, GW A, NWV, GWI, or GWS.91. The AAV particle of any one of embodiments 87-90. wherein [N4] is or comprises TGWV (SEQ ID NO: 5066), TGWA (SEQ ID NO: 5067), SNWV (SEQ ID NO: 5069), NNWV (SEQ ID NO: 5072), TGWI (SEQ ID NO: 5074), or TGWS (SEQ ID NO: 5073).92. The AAV particle of any one of embodiments 87-91. wherein [N4] is or comprises TGWV (SEQ ID NO: 5066).93. The AAV particle of any one of embodiments 87-92, wherein [N 1 ]-[N2]-[N3]-[N4] is or comprises:(i) the amino acid sequence of any one of SEQ ID NOs: 201. 205-209, 211-214. 216, 219, 220.230, 232, 237. 238, 255. 262-265, 274, 283. 286, 290. 291. 293, 301. 306, 307, 308. 309, 314, and 336;(ii) an amino acid sequence comprising any portion of an amino acid sequence in (i), e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 amino acids, e.g., consecutive amino acids, thereof;(iii) an amino acid sequence comprising one, two, or three but no more than four modifications relative to any one of the amino acid sequences in (i); or(iv) an amino acid sequence comprising one, two, or three but no more than four substitutions relative to any one of the amino acid sequences in (i).94. The AAV particle of any one of embodiments 87-93, wherein [N1]-[N2]-[N3]-[N4] is or comprises TNTQDWHRIAQTGWV (SEQ ID NO: 201).95. The AAV particle of any one of embodiments 1-94, wherein [N1]-[N2]-[N3] is present in loop VIII, optionally wherein loop VIII comprises amino acids 580-599 as numbered according to SEQ ID NO: 138 or 981.96. The AAV particle of any one of embodiments 43-50 and 87-95. wherein [N4] is present in loop VIII, optionally wherein loop VIII comprises amino acids 580-599 as numbered according to SEQ ID NO: 138 or 981.97. The AAV particle of any one of embodiments 1-96, wherein [Nl] replaces amino acids 582-585 (e.g.. T582, N583. H584, Q585) of SEQ ID NO: 138.98. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39. 42-49, 51-69, 71-83. and 85-97, wherein [Nl] corresponds to amino acids 582-585 (e.g., T582, N583, T584, Q585) of SEQ ID NO: 981.99. The AAV particle of any one of embodiments 1-98, wherein [Nl] is present at amino acids 582-585, as numbered according to SEQ ID NO: 138 or 981.100. The AAV particle of any one of embodiments 1-99, wherein [Nl] corresponds to positions 582-585 (e.g., T582, N583, T584, Q585) of SEQ ID NO: 981.101. The AAV particle of any one of embodiments 1-100, wherein [N2] replaces amino acids 586-589 (e.g., S586, A587, Q588. A589) of SEQ ID NO: 138.102. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, and 101, wherein [N2] corresponds to amino acids 586-589 (e.g., D586, W587, H588, R589) of SEQ ID NO: 981.103. The AAV particle of any one of embodiments 1-102, wherein [N2] is present at amino acids 586- 589, as numbered according to SEQ ID NO: 138 or 981.104. The AAV particle of any one of embodiments 1-103, wherein [N1]-[N2] replaces amino acids 582- 589 (e.g., T582, N583, H584, Q585, S586, A587, Q588, A589) of SEQ ID NO: 138.105. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, and 101-104, wherein [N1]-[N2] corresponds to amino acids 582-589 (e.g., T582, N583, T584, Q585, D586, W587, H588. R589) of SEQ ID NO: 981.106. The AAV particle of any one of embodiments 1-105, wherein |N 1 HN2J is present at amino acids 582-589, as numbered according to SEQ ID NO: 138 or 981.107. The AAV particle of any one of embodiments 1-106, wherein [N3] replaces amino acids 590-592 (e.g., Q590, A591, and Q592) of SEQ ID NO: 138.108. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49, 51-69, 71-83, 85-99. and 101-107, wherein [N3] corresponds to amino acids 590-592 (e.g., 1590. A591, and Q592) of SEQ ID NO: 981.109. The AAV particle of any one of embodiments 1-108, wherein [N3] is present at amino acids 590- 592, as numbered according to SEQ ID NO: 138 or 981.110. The AAV particle of any one of embodiments 1-109, wherein [N2]-[N3] replaces amino acids 586- 592 (e.g., S586, A587, Q588, A589, Q590, A591, and Q592) of SEQ ID NO: 138.111. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, and 101-110, wherein [N2]-[N3] corresponds to amino acids 586-592 (e.g., D586, W587, H588, R589. 1590, A591. and Q592) of SEQ ID NO: 981.112. The AAV particle of any one of embodiments 1-111, wherein [N2]-[N3] is present at amino acids 586-592, as numbered according to SEQ ID NO: 138 or 981.113. The AAV particle of any one of embodiments 1-112, wherein [N1]-[N2]-[N3] replaces amino acids 582-592 (e.g.. T582. N583, H584, Q585, S586, A587. Q588. A589, Q590, A591. Q592) of SEQ ID NO: 138.114. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49, 51-69, 71-83, 85-99, and 101-113, wherein [N1]-[N2]-[N3] corresponds to amino acids 582-592 (e.g., T582, N583, T584, Q585, D586, W587, H588, R589, 1590, A591, Q592) of SEQ ID NO: 981.115. The AAV particle of any one of embodiments 1-114, wherein [N1]-[N2]-[N3] is present at amino acids 582-592, as numbered according to SEQ ID NO: 138 or 981.116. The AAV particle of any one of embodiments 43-50 and 87-115, wherein [N4] replaces amino acids 593-596 (e.g.. T593. G594, W595, and V596) of SEQ ID NO: 138.117. The AAV particle of any one of embodiments 43-49 and 87-115, wherein | N4| corresponds to amino acids 593-596 (e.g.. T593. G594, W595, and V596) of SEQ ID NO: 138 or 981.118. The AAV particle of any one of embodiments 43-50 and 87-117. wherein [N4] is present at amino acids 593-596. as numbered according to SEQ ID NO: 138 or 981.119. The AAV particle of any one of embodiments 43-50 and 87-118. wherein [N2]-[N3]-[N4] replaces amino acids 586-596 (e.g., S586, A587, Q588. A589, Q590, A591, Q592. T593. G594, W595, and V596) of SEQ ID NO: 138.120. The AAV particle of any one of embodiments 43-49 and 87-119, wherein [N2]-[N3]-[N4] corresponds to amino acids 586-596 (e.g., D586, W587, H588, R589, 1590, A591, Q592, T593, G594, W595, and V596) of SEQ ID NO: 981.121. The AAV particle of any one of embodiments 43-50 and 87-120, wherein [N2]-[N3]-[N4] is present at amino acids 586-596, as numbered according to SEQ ID NO: 138 or 981.122. The AAV particle of any one of embodiments 43-50 and 87-121, wherein [N1]-[N2]-[N3]-[N4] replaces amino acids 582-596 (e.g., T582. N583, H584, Q585, S586, A587, Q588, A589, Q590, A591, Q592, T593, G594, W595, and V596), as numbered according to SEQ ID NO: 138.123. The AAV particle of any one of embodiments 43-49 and 87-122, wherein [N1]-[N2]-[N3]-[N4] corresponds to amino acids 582-596 (e.g.. T582, N583, T584, Q585, D586. W587, H588, R589, 1590, A591, Q592, T593, G594, W595, and V596) of SEQ ID NO: 981.124. The AAV particle of any one of embodiments 43-50 and 87-123, wherein [N1]-[N2]-[N3]-[N4] is present at amino acids 582-596, as numbered according to SEQ ID NO: 138 or 981.125. The AAV particle of any one of embodiments 1-124, wherein [N2] is present immediately subsequent to [Nl],126. The AAV particle of any one of embodiments 1-125, wherein [N3] is present immediately subsequent to [N2] .127. The AAV particle of any one of embodiments 43-50 and 87-126, wherein [N4] is present immediately subsequent to [N3],128. The AAV particle of any one of embodiments 1-127. wherein the AAV capsid variant comprises, from N-terminus to C-terminus, [N1]-[N2]-[N3],129. The AAV particle of any one of embodiments 43-50 and 87-128. wherein the AAV capsid variant comprises, from N-terminus to C-terminus, [N1]-[N2]-[N3]-[N4],130. An AAV particle comprising a viral genome comprising a frataxin (FXN)-encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising:(a) the amino acid sequence of any one of the sequences provided in Table 1, 2A, 2B, 9, 24, 25, or 26;(b) an amino acid sequence comprising at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, or at least 14 consecutive amino acids from any one of the sequences provided in Table 1, 2A, 2B, 9, 24, 25, or 26; or(c) an amino acid sequence comprising at least one, at least two, or at least three but no more than four substitutions relative to any one of the sequences provided in Table 1, 2A, 2B, 9, 24, 25, or 26; or(d) an amino acid sequence comprising at least one, at least two, or at least three but no more than four modifications relative to the amino acid sequence of any one of the sequences provided in Table 1. 2A. 2B. 9, 24. 25, or 26.131. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising:(a) the amino acid sequence of any one of SEQ ID NOs: 201. 205-209, 211-214, 216, 219. 220, 230, 232, 237. 238, 255, 262-265, 274, 283. 286, 290. 291. 293, 301. 306, 307, 308. 309, 314, and 336:(b) an amino acid sequence comprising at least 3, at least 4, at least 5, at least 6, at least 7, at least8, at least 9, at least 10, at least 11, at least 12, at least 13, or at least 14 consecutive amino acids from any one of SEQ ID NOs: 201, 205-209, 211-214, 216, 219, 220, 230, 232, 237, 238, 255, 262-265, 274, 283, 286, 290, 291, 293, 301, 306. 307, 308, 309, 314, and 336;(c) an amino acid sequence comprising at least one, at least two, or at least three but no more than four substitutions, relative to the amino acid sequence of any one of SEQ ID NOs: 201, 205-209, 211-214, 216, 219, 220, 230, 232, 237, 238. 255, 262-265, 274, 283, 286. 290, 291, 293. 301, 306, 307, 308, 309, 314. and 336; or(d) an amino acid sequence comprising at least one, at least two, or at least three but no more than four modifications relative to the amino acid sequence of any one of SEQ ID NOs: 201. 205-209, 211-214, 216, 219, 220, 230. 232, 237, 238. 255, 262-265. 274, 283, 286. 290, 291, 293. 301, 306. 307, 308, 309, 314. and 336.132. The AAV particle of embodiment 130 or 131, wherein the AAV capsid variant does not comprise at least 3, at least 4. at least 5. at least 6, at least 7, at least 8, or at least 9 consecutive amino acids from TNHQSAQAQ (SEQ ID NO: 5100), optionally wherein the TNHQSAQAQ (SEQ ID NO: 5100) corresponds to amino acids 582-592 of SEQ ID NO: 138.133. The AAV particle of any one of embodiments 130-132, wherein the AAV capsid variant does not comprise: TNH, TNHQ (SEQ ID NO: 4760), TNHQS (SEQ ID NO: 5101), TNHQSA (SEQ ID NO: 5102). TNHQSAQ (SEQ ID NO: 5103), TNHQSAQA (SEQ ID NO: 5104), TNHQSAQAQ (SEQ ID NO: 5100), NHQ, NHQS (SEQ ID NO: 5105), NHQSA (SEQ ID NO: 5106), NHQSAQ (SEQ ID NO:5107), NHQSAQA (SEQ ID NO: 5108), NHQSAQAQ (SEQ ID NO: 5109), HQS, HQSA (SEQ ID NO: 5110), HQSAQ (SEQ ID NO: 5111), HQSAQA (SEQ ID NO: 5112), HQSAQAQ (SEQ ID NO: 5113), QSA, QSAQ (SEQ ID NO: 5114), QSAQA (SEQ ID NO: 5115), QSAQAQ (SEQ ID NO: 5116), SAQA (SEQ ID NO: 5117), or SAQAQ (SEQ ID NO: 5118).134. The AAV particle of any one of embodiments 130-124, wherein the AAV capsid variant comprises an amino acid sequence comprising at least 3, at least 4, at least 5, at least 6, at least 7. at least 8, at least9. at least 10, at least 11, at least 12, at least 13, or at least 14 consecutive amino acids from any one of SEQ ID NOs: 201, 205-209, 211-214, 216, 219, 220, 230, 232. 237, 238, 255, 262-265, 274. 283, 286, 290, 291, 293. 301, 306, 307. 308, 309, 314, and 336.135. The AAV particle of any one of embodiments 130-134. wherein the at least 3 consecutive amino acids comprise TQD.136. The AAV particle of any one of embodiments 130-135, wherein the at least 4 consecutive amino acids comprise TQDW (SEQ ID NO: 4684).137. The AAV particle of any one of embodiments 130-136, wherein the at least 5 consecutive amino acids comprise TQDWH (SEQ ID NO: 4685).138. The AAV particle of any one of embodiments 130-137, wherein the at least 6 consecutive amino acids comprise TQDWHR (SEQ ID NO: 4686).139. The AAV particle of any one of embodiments 130-138. wherein the at least 7 consecutive amino acids comprise TQDWHRI (SEQ ID NO: 941).140. The AAV particle of any one of embodiments 130-134. wherein the at least 3 consecutive amino acids comprise TNT.141. The AAV particle of any one of embodiments 130-134 and 140, wherein the at least 4 consecutive amino acids comprise TNTQ (SEQ ID NO: 4688).142. The AAV particle of any one of embodiments 130-134, 140. and 141, wherein the at least 5 consecutive amino acids comprise TNTQD (SEQ ID NO: 5119).143. The AAV particle of any one of embodiments 130-134 and 140-142, wherein the at least 6 consecutive amino acids comprise TNTQDW (SEQ ID NO: 5120).144. The AAV particle of any one of embodiments 130-134 and 140-143, wherein the at least 7 consecutive amino acids comprise TNTQDWH (SEQ ID NO: 5121).145. The AAV particle of any one of embodiments 130-134 and 140-144, wherein the at least 8 consecutive amino acids comprise TNTQD WHR (SEQ ID NO: 4898).146. The AAV particle of any one of embodiments 130-134 and 140-145, wherein the at least 9 consecutive amino acids comprise TNTQDWHRI (SEQ ID NO: 746).147. The AAV particle of any one of embodiments 130-146. wherein the AAV capsid variant comprises an amino acid sequence comprising at least one. at least two. or at least three but no more than four modifications relative to the amino acid sequence of any one of SEQ ID NOs: 201, 205-209. 211-214,216, 219, 220, 230, 232, 237, 238, 255, 262-265, 274, 283, 286, 290, 291, 293, 301, 306, 307, 308, 309, 314, and 336.148. The AAV particle of any one of embodiments 130-147, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least two, or at least three but no more than four modifications relative to the amino acid sequence of TQDWHRI (SEQ ID NO: 941).149. The AAV particle of any one of embodiments 130-147, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one. at least two. or at least three but no more than four modifications relative to the amino acid sequence of TNTQDWHRI (SEQ ID NO: 746).150. The AAV particle of any one of embodiments 130-149. wherein the AAV capsid variant comprises an amino acid sequence comprising at least one. at least two. or at least three but no more than four modifications relative to the amino acid sequence of ATNTQDWHRIAQT (SEQ ID NO: 744).151. The AAV particle of any one of embodiments 130-150, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least two. or at least three but no more than four substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 201, 205-209, 211-214, 216. 219, 220, 230, 232, 237, 238, 255, 262-265, 274, 283, 286, 290, 291. 293, 301, 306. 307, 308, 309, 314. and 336.152. The AAV particle of any one of embodiments 130-149 and 151, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least tw o. or at least three but no more than four substitutions relative to the amino acid sequence of TQDWHRI (SEQ ID NO: 941).153. The AAV particle of any one of embodiments 130-149, 151, and 152, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least two, or at least three but no more than four substitutions relative to the amino acid sequence of TNTQDWHRI (SEQ ID NO: 746).154. The AAV particle of any one of embodiments 130-153, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one. at least two. or at least three but no more than four substitutions relative to the amino acid sequence of ATNTQDWHRIAQT (SEQ ID NO: 744).155. The AAV particle of any one of embodiments 1-154, wherein the AAV capsid variant comprises the amino acid sequence of any one of SEQ ID NOs: 201. 205-209, 211-214. 216, 219, 220. 230, 232, 237, 238, 255, 262-265, 274, 283. 286, 290, 291. 293, 301, 306. 307, 308. 309, 314, and 336.156. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49, 51-69, 71-83, 85-99, and 101-155, wherein the AAV capsid variant comprises the amino acid sequence of TQDWHRI (SEQ ID NO: 941), optionally wherein the amino acid sequence replaces amino acids 584-590 of SEQ ID NO: 138.157. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, and 101-156, wherein the AAV capsid variant comprises the amino acid sequence of TQDWHRI (SEQ ID NO: 941), optionally wherein the amino acid sequence corresponds to amino acids 584-590 of SEQ ID NO: 981.158. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, 101-149. 151-153, and 155-157. wherein the AAV capsid variant comprises an amino acid sequence encoded by:(i) the nucleotide sequence of SEQ ID NO: 942;(ii) a nucleotide sequence comprising at least one, at least two, at least three, at least four, at least five, at least six, or at least seven modifications, but no more than ten modifications, relative to the nucleotide sequence of SEQ ID NO: 942; or(iii) a nucleotide sequence comprising at least one, at least two. at least three, at least four, at least five, at least six, or at least seven, but no more than ten different nucleotides relative to the nucleotide sequence of SEQ ID NO: 942.159. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49, 51-69, 71-83, 85-99, and 101-158, wherein the AAV capsid variant comprises an amino acid sequence encoded by:(i) the nucleotide sequence of SEQ ID NO: 747;(ii) a nucleotide sequence comprising at least one, at least two, at least three, at least four, at least five, at least six, or at least seven modifications, but no more than ten modifications, relative to the nucleotide sequence of SEQ ID NO: 747; or(iii) a nucleotide sequence comprising at least one, at least two, at least three, at least four, at least five, at least six, or at least seven, but no more than ten different nucleotides relative to the nucleotide sequence of SEQ ID NO: 747.160. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, and 101-149, 151-153, and 155-158, wherein the nucleotide sequence encoding the AAV capsid variant comprises:(i) the nucleotide sequence of SEQ ID NO: 942;(ii) a nucleotide sequence comprising at least one, at least two, at least three, at least four, at least five, at least six, or at least seven modifications, but no more than ten modifications, relative to the nucleotide sequence of SEQ ID NO: 942; or(iii) a nucleotide sequence comprising at least one, at least two. at least three, at least four, at least five, at least six, or at least seven, but no more than ten different nucleotides relative to the nucleotide sequence of SEQ ID NO: 942.161. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, and 101-160, wherein the nucleotide sequence encoding the AAV capsid variant comprises:(i) the nucleotide sequence of SEQ ID NO: 747;(ii) a nucleotide sequence comprising at least one, at least two, at least three, at least four, at least five, at least six. or at least seven modifications, but no more than ten modifications, relative to the nucleotide sequence of SEQ ID NO: 747; or(iii) a nucleotide sequence comprising at least one, at least two, at least three, at least four, at least five, at least six. or at least seven, but no more than ten different nucleotides relative to the nucleotide sequence of SEQ ID NO: 747.162. The AAV particle of any one of embodiments 130-157, w herein the amino acid sequence provided in Table 1. 2 A, 2B. 9, 24. 25, or 26 is present in loop VIII, optionally wherein loop VIII comprises amino acids 580-599. as numbered according to SEQ ID NO: 138 or 981.163. The AAV particle of any one of embodiments 130-157, wherein the amino acid sequence provided in Table 1, 2A, 2B, 9, 24, 25, or 26 replaces amino acids 584, 585, 586, 587, 588, 589. and / or 590 (e.g., H584. Q585, S586, A587, Q588, A589, and / or Q590), as numbered according to the amino acid sequence of SEQ ID NO: 138.164. The AAV particle of any one of embodiments 130-157, wherein the amino acid sequence provided in Table 1, 2A, 2B, 9, 24, 25, or 26 is present at amino acids 584. 585, 586, 587, 588, 589, and / or 590, as numbered according to the amino acid sequence of SEQ ID NO: 981.165. The AAV particle of any one of embodiments 130-157, wherein the amino acid sequence provided in Table 1, 2A, 2B, 9, 24, 25. or 26 corresponds to amino acids 584-590 (e.g.. T584. Q585, D586, W587. H588, R589, and / or 1590), numbered according to the amino acid sequence of SEQ ID NO: 981.166. The AAV particle of any one of embodiments 121-157. wherein the amino acid sequence provided in Table 1, 2A, 2B, 9, 24, 25. or 26 replaces amino acids 582, 583, 584. 585, 586. 587, 588, 589. and / or 590 (e.g.. T582. N583. H584, Q585, S586, A587, Q588. A589, and / or Q590) of SEQ ID NO: 138.167. The AAV particle of any one of embodiments 121-157, wherein the amino acid sequence provided in Table 1, 2A, 2B, 9, 24, 25, or 26 is present at amino acids 582. 583, 584, 585, 586, 587, 588, 589, and / or 590, as numbered according to the amino acid sequence of SEQ ID NO: 981.168. The AAV particle of any one of embodiments 121-157, wherein the amino acid sequence provided in Table 1, 2A, 2B, 9, 24, 25. or 26 replaces amino acids 582, 583, 584. 585, 586, 587, 588, 589, 590, 591, 592, 593. 594, 595, and / or 596 (e.g., T582, N583. H584, Q585, S586, A587, Q588. A589, Q590, A591, Q592, T593, G594, W595, and / or V5965) of SEQ ID NO: 138.169. The AAV particle of any one of embodiments 121-157. wherein the amino acid sequence provided in Table 1, 2A, 2B, 9, 24, 25. or 26 is present at amino acids 582. 583, 584. 585, 586, 587. 588, 589, 590. 591, 592, 593. 594, 595. and / or 596, as numbered according to the amino acid sequence of SEQ ID NO: 981.170. The AAV particle of any one of embodiments 1-169, wherein the AAV capsid variant comprises one. two, three, four, five, or all of:(i) an amino acid other than H at position 584 (e.g.. T);(ii) an amino acid other than S at position 586 (e.g., D);(iii) an amino acid other than A at position 587 (e.g., W);(iv) an amino acid other than Q at position 588 (e.g., H);(v) an amino acid other than A at position 589 (e.g., R); and / or(vi) an amino acid other than Q at position 590 (e.g., I); wherein the amino acids in (i)-(vi) are numbered according to SEQ ID NO: 138.171. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising one, two, three, four, five, or all of:(i) an amino acid other than H at position 584 (e.g., T);(ii) an amino acid other than S at position 586 (e.g., D);(iii) an amino acid other than A at position 587 (e.g.. W);(iv) an amino acid other than Q at position 588 (e.g.. H);(v) an amino acid other than A at position 589 (e.g., R); and / or(vi) an amino acid other than Q at position 590 (e.g.. I); wherein the amino acids in (i) and (vi) are numbered according to SEQ ID NO: 138.172. The AAV particle of any one of embodiments 1-171, wherein the AAV capsid variant comprises one, two, three, four, five, or all of: T at position 584, D at position 586, W at position 587, H at position 588, R at position 589, and / or I at position 590, as numbered according to SEQ ID NO: 981.173. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising one, two, three, four, five, or all of: T at position 584, D at position 586, W at position 587, H at position 588, R at position 589. and / or I at position 590, as numbered according to SEQ ID NO: 981.174. The AAV particle of any one of embodiments 1-173, wherein the AAV capsid variant comprises one, two, three, four, five, or all of the substitutions H584T, S586D, A587W, Q588H. A589R. and / or Q590I, as numbered according to SEQ ID NO: 138.175. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g.. an AAV9 capsid variant) comprising one. two, three, four, five or all of the substitutions H584T. S586D, A587W. Q588H, A589R, and / or Q590I, as numbered according to SEQ ID NO: 138.176. The AAV particle of any one of embodiments 1-175, wherein the AAV capsid variant comprises an amino acid other than H at position 584 (e.g., T), an amino acid other than S at position 586 (e.g., D). an amino acid other than A at position 587 (e.g., W), an amino acid other than Q at position 588 (e.g., H), an amino acid other than A at position 589 (e.g., R), and an amino acid other than Q at position 590 (e.g., I), as numbered according to SEQ ID NO: 138.177. The AAV particle of any one of embodiments 1-176, wherein the AAV capsid variant comprises T at position 584, D at position 586, W at position 587, H at position 588, R at position 589, and I at position 590, as numbered according to SEQ ID NO: 981.178. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49. 51-69, 71-83, 85-98, and 100-164, wherein the AAV capsid variant comprises an amino acid at each of positions 584, 586, 587, 588. 589, and 590 that is different from the amino acid at the corresponding positions in SEQ ID NO: 138.179. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, and 101-178. wherein the AAV capsid variant comprises an amino acid at each of positions 582, 583, 584, 586. 587, 588, and 589 that is different from the amino acid at the corresponding positions in SEQ ID NO: 138.180. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49, 51-69, 71-83, 85-99, and 101-179, wherein the AAV capsid variant comprises an amino acid at each of positions 582, 583, 584, 586, 587, 588, 589. 590, 591, 592, 593, 594, 595, and 596 that is different from the amino acid at the corresponding positions in SEQ ID NO: 138.181. The AAV particle of any one of embodiments 1-181, wherein the AAV capsid variant comprises the substitutions H584T. S586D. A587W, Q588H, A589R, and Q590I. as numbered according to SEQ ID NO: 138.182. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising T at position 584, D at position 586, W at position 587, H at position 588, R at position 589. and I at position 590, as numbered according to SEQ ID NO: 981.183. An AAV particle comprising a viral genome comprising a frataxin (FXN)-encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising the substitutions H584T, S586D, A587W, Q588H. A589R. and Q590I, as numbered according to SEQ ID NO: 138.184. The AAV particle of any one of embodiments 1-183, wherein the AAV capsid variant further comprises an amino acid other than A position 581, as numbered according to SEQ ID NO: 138 or 981.185. The AAV particle of any one of embodiments 1-184, wherein the AAV capsid variant further comprises a T at position 581 or a V at position 581, as numbered according to SEQ ID NO: 138 or 981.186. The AAV particle of any one of embodiments 1-185, wherein the AAV capsid variant comprises the substitutions A581T or A581V, as numbered according to SEQ ID NO: 138 or 981.187. The AAV particle of any one of embodiments 1, 3-7, 9-15, 17-20, 22-38, 40-48, 50, 130-134, 147, 151, 155, 162. 163, 166-177, and 181-186, wherein the AAV capsid variant comprises an amino acid other than Q at position 585, as numbered according to SEQ ID NO: 138.188. The AAV particle of any one of embodiments 1, 3-7, 9-15, 17-20, 22-38, 40-48, 50, 130-134, 147, 151, 155, 162. 163, 166-177. and 181-187, wherein the AAV capsid variant comprises the amino acid K at position 585, as numbered according to SEQ ID NO: 138.189. The AAV particle of any one of embodiments 1-189, wherein the AAV capsid variant further comprises:(i) a modification in loop I, II, IV, and / or VI; and / or(ii) a substitution at position K449, e.g., a K449R substitution, as numbered according to SEQ ID NO: 138 or 981.190. The AAV particle of any one of embodiments 1-189, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least two, or at least three modifications, but not more than 30. not more than 20, or not more than 10 modifications, relative to the amino acid sequence of SEQ ID NO: 138.191. The AAV particle of any one of embodiments 1-190, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least two, or at least three, but no more than not more than 30, not more than 20, or not more than 10 substitutions relative to the amino acid sequence of SEQ ID NO: 138.192. The AAV particle of any one of embodiments 1-191, wherein the AAV capsid variant an amino acid sequence with at least 90% (e g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99%) sequence identity to SEQ ID NO:138.193. The AAV particle of embodiment 192, wherein the AAV capsid variant an amino acid sequence with at least 95% (e.g., at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity to SEQ ID NO: 138.194. The AAV particle of any one of embodiments 1-193, wherein the AAV capsid variant comprises an amino acid sequence encoded by a sequence with at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity to SEQ ID NO: 137.195. The AAV particle of embodiment 194. wherein the AAV capsid variant comprises an amino acid sequence encoded by a sequence with at least 90% (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity to SEQ ID NO: 137.196. The AAV particle of any one of embodiments 1-195, wherein the AAV capsid variant comprises a VP1 protein, a VP2 protein, and a VP3 protein in an about 1: 1 : 10 ratio.197. The AAV particle of any one of embodiments 1-196, wherein the AAV capsid variant comprises amino acids 138-736, e.g., a VP2, of SEQ ID NO: 981, or a sequence with at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity thereto.198. The AAV particle of any one of embodiments 1-197, wherein the AAV capsid variant comprises amino acids 203-736, e.g., a VP3, of SEQ ID NO: 981, or a sequence with at least 80% (e.g., at least 80%, at least 85%. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%. or at least 99%) sequence identity thereto.199. The AAV particle of any one of embodiments 1-198, wherein the AAV capsid variant comprises an amino acid sequence that is at least 80% (e.g.. at least 80%, at least 85%. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to amino acids 138-736, e.g.. a VP2, of SEQ ID NO: 138.200. The AAV particle of any one of embodiments 1-199, wherein the AAV capsid variant comprises an amino acid sequence that is at least 80% (e.g., at least 80%. at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99%) identical to amino acids 203-736, e.g.. a VP3, of SEQ ID NO: 138.201. The AAV particle of any one of embodiments 1-3, 5-8, 10-16, 18-21, 23-39, 42-49, 51-69, 71-83, 85-99, 101-186, and 189-200, wherein the AAV capsid variant comprises an amino acid sequence comprising at least 3, at least 4, at least 5, at least 6, or all 7 consecutive amino acids from the amino acid sequence of TQDWHRI (SEQ ID NO: 941), wherein:(i) the at least 3 consecutive amino acids comprise TQD;(ii) the at least 4 consecutive amino acids comprise TQDW (SEQ ID NO: 4684);(iii) the at least 5 consecutive amino acids comprise TQDWH (SEQ ID NO: 4685);(iv) the at least 6 consecutive amino acids comprise TQDWHR (SEQ ID NO: 4686); or(v) the 7 consecutive amino acids comprise TQDWHRI (SEQ ID NO: 941); wherein the AAV capsid variant comprises: (a) a VP1 protein comprising the amino acid sequence of SEQ ID NO: 981; (b) a VP2 protein comprising amino acids 138-736 of SEQ ID NO: 981: (c) a VP3 protein comprising amino acids 203-736 of SEQ ID NO: 981; or (d) an amino acid sequence with at least 80% (e.g.. at least 80%, at least 85%, at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99%) sequence identity to any one of tire amino acid sequences in (a)-(c).202. The AAV particle of embodiment 201, wherein the AAV capsid variant comprises an amino acid sequence with at least 90% (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity to any one of the amino acid sequences in (a)-(c).203. The AAV particle of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85-99, 101-186, and 189-202, wherein the AAV capsid variant comprises 1, 2, or 3 substitutions relative to the amino acid sequence of TQDWHRI (SEQ ID NO: 941), wherein the AAV capsid variant comprises an amino acid sequence at least 90% (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981.204. The AAV particle of any one of embodiments 1-203. wherein the AAV capsid variant comprises the amino acid sequence of any one of SEQ ID NO: 981, or an amino acid sequence with at least 90% (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%. at least 97%, at least 98%, or at least 99%) sequence identity thereto.205. The AAV particle of any one of embodiments 1-204, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least two, or at least three modifications, but not more than 30, not more than 20 or not more than 10 modifications relative to the amino acid sequence of SEQ ID NO: 981.206. The AAV particle of any one of embodiments, 1-205, wherein the AAV capsid variant comprises an amino acid sequence comprising at least one, at least two or at least three, but not more than 30, not more than 20 or not more than 10 substitutions, relative to the amino acid sequence of SEQ ID NO: 981.207. The AAV particle of any one of embodiments 1-206, wherein the AAV capsid variant comprises an amino acid sequence encoded by the nucleotide sequence of SEQ ID NO: 983, or a nucleotide sequence with at least 80% (e.g.. at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99%) sequence identity thereto.208. The AAV particle of embodiment 207. wherein the AAV capsid variant comprises an amino acid sequence encoded by the nucleotide sequence of SEQ ID NO: 983.209. The AAV particle of embodiment 207. wherein the AAV capsid variant is encoded by a codon- optimized nucleotide sequence.210. An AAV particle comprising an AAV capsid variant (e.g., an AAV9 capsid variant) comprising the amino acid sequence of any one of embodiments 1-3, 5-8, 10-16. 18-21, 23-39, 42-49. 51-69, 71-83, 85- 99, 101-186, and 189, and further comprising an amino acid sequence at least 95% (e.g.. at least 95%, at least 96%, at least 97%, at least 98%. or at least 99%) identical to SEQ ID NO: 981.211. An AAV particle comprising a viral genome comprising a frataxin (FXN)-encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g.. an AAV9 capsid variant) comprising the amino acid sequence of SEQ ID NO: 981.212. An AAV particle comprising a viral genome comprising a frataxin (FXN)-encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising an amino acid sequence encoded by the nucleotide sequence of SEQ ID NO: 983, or a nucleotide sequence at least 95% identical (e.g., at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto.213. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising amino acids 203-736 of SEQ ID NO: 981, or an amino acid sequence at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical thereto, wherein the AAV capsid variant comprises T at position 584, D at position 586, W at position 587, H at position 588, R at position 589, and I at position 590, as numbered according to SEQ ID NO: 981.214. The AAV particle of embodiment 213. wherein the AAV capsid variant comprises amino acids 203- 736 of SEQ ID NO: 981.215. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising amino acids 203-736 of SEQ ID NO: 981.216. An AAV particle comprising a viral genome comprising a frataxin (FXN)-encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising amino acids 138-736 of SEQ ID NO: 981. or an amino acid sequence at least 80% (e.g., at least 80%. at least 85%, at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99%) identical thereto, wherein the AAV capsid variant comprisesT at position 584, D at position 586, W at position 587, H at position 588, R at position 589, and I at position 590, as numbered according to SEQ ID NO: 981.217. The AAV particle any one of embodiments 213-216, wherein the AAV capsid variant comprises amino acids 138-736 of SEQ ID NO: 981.218. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising amino acids 138-736 of SEQ ID NO: 981.219. An AAV particle comprising a viral genome comprising a frataxin (FXN) -encoding sequence (e.g., encoding a human FXN protein) and an AAV capsid variant (e.g., an AAV9 capsid variant) comprising the amino acid sequence of SEQ ID NO: 981. or an amino acid sequence at least 80% (e.g., at least 80%. at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99%) identical thereto, wherein the AAV capsid variant comprises T at position 584, D at position 586. W at position 587. H at position 588. R at position 589, and I at position 590. as numbered according to SEQ ID NO: 981.220. The AAV particle any one of embodiments 213-219, wherein the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 981.221. The AAV particle of any one of embodiments 1-220, wherein the AAV capsid variant has increased tropism for a CNS cell or tissue, e.g., a brain cell, brain tissue, spinal cord cell, or spinal cord tissue, relative to the tropism of an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138.222. The AAV particle of any one of embodiments 1-221, wherein the AAV capsid variant transduces a brain region, e.g., sensory cortex, motor cortex, putamen, thalamus, caudate, hippocampus, and / or cerebellum; optionally wherein the level of transduction is at least 39, at least 50, at least 100, at least 120, at least 132, at least 146, at least 150, at least 161, at least 174, at least 175, at least 200, at least 225, at least 250, at least 275, at least 283, at least 300, at least 350, at least 400, at least 450, at least 500, at least 525, at least 528, or at least 550-fold greater as compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138, e.g.. when measured by an assay, e.g., an immunohistochemistry assay or a qPCR or ddPCR assay, e.g.. as described in Example 2.223. The AAV particle of any one of embodiments 1-222, which is enriched at least 10. at least 14, at least 20, at least 24, at least 50. at least 100. at least 150. at least 200. at least 250. at least 300. at least350, at least 400, at least 425, at least 450, or at least 460-fold in the brain compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138, e.g., when measured by an assay as described in Example 1 or 3.224. The AAV particle of any one of embodiments 1-223, which is enriched at least 200, at least 300, at least 400, at least 425, at least 450, or at least 460-fold in the brain compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138, e.g.. when measured by an assay as described in Example 1.225. The AAV particle of any one of embodiments 1-224, which is enriched in the brain of at least two or at least three species, e.g., a non-human primate and rodent (e.g.. mouse), e.g., as compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138.226. The AAV particle of any one of embodiments 1-225, which is enriched at least 2, at least 3, at least 5, at least 10. at least 15, at least 20. at least 25, at least 30, at least 35. at least 40, at least 45. at least 50, at least 55. at least 60, at least 65, at least 70. at least 75, at least 80. at least 85, at least 90, at least 95. at least 100, at least 105, at least 115, at least 120, at least 125, at least 130, at least 135, at least 140, at least 145. at least 150. at least 155. at least 160. at least 165. at least 170. at least 175. at least 180, at least 190, at least 200, at least 205, or at least 210-fold in the brain of at least two or at least three species, e.g., a non-human primate and rodent (e.g., mouse), compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138, e.g., when measured by an assay as described in Example 1 or 4.227. The AAV particle of embodiment 225 or 226, wherein the at least two or at least three species comprise Macaca fascicularis, CMorocebus sabaeus, Callithrix jacchus, and / or mouse (e.g., outbred mice).228. The AAV particle of any one of embodiments 1-227, which is enriched at least 2, at least 3, at least 4. at least 5, at least 10, at least 15, at least 17. at least 20, at least 50, at least 75, at least 100, at least 103, at least 107, at least 125, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 450, at least 500, at least 750, at least 1000, at least 1200-fold in the brain compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 981, e.g., when measured by an assay as described in Example 3.229. The AAV particle of any one of embodiments 1-228, which delivers an increased level of FXN to a brain region, optionally wherein the FXN level is increased by at least 39, at least 50, at least 100, at least 120, at least 132, at least 146, at least 150, at least 161, at least 174, at least 175, at least 200, at least 225,at least 250, at least 275, at least 283, at least 300, at least 350, at least 400, at least 450, at least 500, at least 525, at least 528, or at least 550-fold as compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138, e.g., when measured by an assay, e.g., a qRT- PCR, a ddPCR, or a qPCR assay (e g., as described in Example 2).230. The AAV particle of any one of embodiments 1-229, which delivers an increased level of viral genomes to a brain region, optionally wherein the level of viral genomes is increased by at least 2, at least 5, at least 7, at least 10, at least 15, at least 19, at least 20, at least 22, or at least 25-fold as compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138. e.g., when measured by an assay, e.g., a qRT-PCR or a qPCR assay (e.g.. as described in Example 2).231. The AAV particle of embodiment 229 or 230, wherein the brain region is a sensory cortex, motor cortex, putamen, thalamus, caudate, hippocampus, and / or cerebellum.232. The AAV particle of any one of embodiments 1-231, which is enriched at least 5. at least 10. at least 50, at least 100, at least 115, at least 120, at least 150, at least 175, at least 200, at least 207, at least 225, at least 250, or at least 275-fold in the spinal cord compared to an AAV particle comprising an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138, e.g., when measured by an assay as described in Example 1 or 2.[Embodiments 233-311 are intentionally absent.]312. The AAV particle of any one of embodiments 1-232, wherein the viral genome is single-stranded.313. The AAV particle of any one of embodiments 1-232, wherein the viral genome is self- complementary.314. The AAV particle of any one of embodiments 1-232, embodiment 312, or embodiment 313, wherein the viral genome further comprises a nucleotide sequence encoding a Rep protein, e g., a non-structural protein, wherein the Rep protein comprises a Rep78 protein, a Rep68 protein, a Rep52 protein, and / or a Rep40 protein (e.g., a Rep78 protein and a Rep52 protein).315. The AAV particle of any one of embodiments 1-232, embodiment 312, or embodiment 313, wherein the AAV particle further comprises a nucleotide sequence encoding a Rep protein, e.g., a non-structural protein, wherein the Rep protein comprises a Rep78 protein, a Rep68 protein, a Rep52 protein, and / or a Rep40 protein (e.g., a Rep78 protein and a Rep52 protein).316. The AAV particle of embodiment 314 or 315, wherein the Rep78 protein, the Rep68 protein, the Rep52 protein, and / or the Rep40 protein is encoded by at least one Rep gene.317. The AAV particle of any one of embodiments 1-232 and 312-316, wherein the AAV particle is an isolated AAV particle.318. The AAV particle of any one of embodiments 1-232 and 312-317, wherein the AAV particle is a recombinant AAV particle.319. A cell, e.g.. a host cell, comprising the AAV particle of any one of embodiments 1-232 and 312- 318.320. The cell of embodiment 319, wherein the cell is a mammalian cell or an insect cell.321. The cell of embodiment 319 or 320, wherein the cell is a cell of a brain region or a spinal cord region, optionally wherein the cell is a cell of the sensory cortex, motor cortex, putamen. thalamus, caudate, hippocampus, or cerebellum.[Embodiments 322-325 are intentionally absent],326. A pharmaceutical composition comprising the AAV particle of any one of embodiments 1-232 and 312-318, and a pharmaceutically acceptable excipient.327. A method of delivering FXN to a cell or tissue (e.g., a CNS cell or CNS tissue), comprising administering an effective amount of the pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318.328. The method of embodiment 327, wherein the cell is a cell of a brain region or a spinal cord region, optionally a cell of the frontal cortex, sensory cortex, motor cortex, caudate, cerebellar cortex, cerebral cortex, brain stem, hippocampus, or thalamus.329. The method of embodiment 327 or 328, wherein the cell is a neuron, a sensory neuron, and / or a motor neuron.330. The method of any one of embodiments 327-329. wherein the cell or tissue is within a subject.331. The method of embodiment 330. wherein the subject has, has been diagnosed with having, or is at risk of having a genetic disorder.332. The method of embodiment 330 or embodiment 331, wherein the subject has, has been diagnosed with having, or is at risk of having a neurological disorder.333. The method of embodiment 330 or embodiment 331, wherein the subject has, has been diagnosed with having, or is at risk of having a neurodegenerative disorder.334. The method of embodiment 330 or embodiment 331, wherein the subject has, has been diagnosed with having, or is at risk of having a muscular disorder or a neuromuscular disorder.335. A method of treating a subject having or diagnosed with having a genetic disorder, comprising administering to the subject an effective amount of the pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318.336. A method of treating a subject having or diagnosed with having a neurological disorder, comprising administering to the subject an effective amormt of the pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318.337. A method of treating a subject having or diagnosed with having a muscular disorder or a neuromuscular disorder, comprising administering to the subject an effective amormt of the pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318.338. A method of treating a subject having or diagnosed with having a neurodegenerative disorder, comprising administering to the subject an effective amount of the pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318.339. The method of any one of embodiments 327-338. wherein the genetic disorder, neurological disorder, neurodegenerative disorder, muscular disorder, or neuromuscular disorder is a disorder associated with FXN deficiency (e.g.. Friedreich’s ataxia).340. The method of any one of embodiments 335-339. where treating comprises prevention of progression of the disorder in the subject.341. The method of any one of embodiments 330-340. wherein the subject is a human.342. The method of any one of embodiments 330-341, wherein the AAV particle or the pharmaceutical composition is administered to the subject intravenously, via intra-cisterna magna injection (ICM), intracerebrally, intrathecally, intracerebroventricularly, via intraparenchymal administration, intraarterially, or intramuscularly.343. The method of any one of embodiments 330-342. wherein the AAV particle or pharmaceutical composition is administered to the subject via focused ultrasound (FUS), e.g.. coupled with the intravenous administration of microbubbles (FUS-MB), or MRI-guided FUS coupled with intravenous administration.344. The method of any one of embodiments 330-343. wherein the AAV particle or pharmaceutical composition is administered to the subject intravenously.345. The method of any one of embodiments 330-344, wherein the AAV particle or pharmaceutical composition is administered to the subject via intra-cistema magna injection (ICM).346. The method of any one of embodiments 330-345, wherein the AAV particle or pharmaceutical composition is administered to the subject intraarterially.347. The method of any one of embodiments 342-346, wherein administration of the AAV particle or pharmaceutical composition results in an increased expression of a FXN gene, mRNA, protein, or combination thereof.348. The method of any one of embodiments 342-346, wherein administration of the AAV particle or pharmaceutical composition results in an increased activity of a FXN gene, mRNA, protein, or a combination thereof.349. The pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318, for use in a method of delivering FXN to a cell or tissue.350. The pharmacal composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318, for use in a method of treating a genetic disorder, a neurological disorder, a neurodegenerative disorder, a muscular disorder, or a neuromuscular disorder.351. The pharmacal composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318, for use in the manufacture of a medicament.352. Use of the pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318 in the manufacture of a medicament.353. Use of the pharmaceutical composition of embodiment 326 or the AAV particle of any one of embodiments 1-232 and 312-318 in the manufacture of a medicament for treating a genetic disorder, a neurological disorder, a neurode generative disorder, a muscular disorder, or a neuromuscular disorder.354. An adeno-associated virus (AAV) particle comprising an AAV capsid variant and a viral genome, wherein the viral genome comprises a frataxin (FXN)-encoding sequence and the AAV capsid variant comprises an amino acid sequence having the formula [N1]-[N2]-[N3] (SEQ ID NO: 4681) in loop VIII; wherein [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682); and wherein:(i) [Nl] comprises amino acids Xi, X2, X3. and X4, wherein X4is Q. K, E, S. P, R, N. or H; and / or(ii) [N3] comprises amino acids X5, X6, and X?, wherein X5is I, V, T, M, S, N, L, or F.355. The AAV particle of embodiment 354, wherein the AAV capsid variant is an AAV9 capsid variant.356. The AAV particle of embodiment 354 or embodiment 355, wherein the AAV capsid variant comprises an amino acid sequence that is at least 95% (e.g., at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to amino acids 203-736 of SEQ ID NO: 981.357. The AAV particle of any one of embodiments 354-356, wherein loop VIII comprises amino acids 580-599 as numbered according to SEQ ID NO: 981.358. The AAV particle of any one of embodiments 354-357, wherein:(i) Xi is T, S, R, A, I, C, N. K, L, or Q;(ii) X2is N, T. G, V, S. Y, K. I. H, D, or F; and(iii) X3is T, N, K, D, I, S, P, A. Y, E, V, L, M, R, H. Q, or C.359. The AAV particle of any one of embodiments 354-358. wherein:(i) X6is A, Y, P, N, S, T, G, E, V, W, F, or Q; and(ii) X7is Q, G, N. K, H. R, E, L. P, or M.360. The AAV particle of any one of embodiments 354-359, wherein [Nl] comprises the amino acid sequence of TNTQ (SEQ ID NO: 4688).361. The AAV particle of any one of embodiments 354-360, wherein [N3] comprises the amino acid sequence of IAQ.362. The AAV particle of any one of embodiments 354-361, wherein [N1]-N2]-[N3] comprises the amino acid sequence of TNTQD WHRI AQ (SEQ ID NO: 343).363. The AAV particle of any one of embodiments 354-362, wherein:(i) [Nl] is present at amino acids 582-585;(ii) [N2] is present at amino acids 586-589; and(iii) [N3] is present at amino acids 590-592; wherein the amino acids are numbered according to SEQ ID NO: 981.364. The AAV particle of any one of embodiments 354-363, further comprising [N4] comprising amino acids X8. X9. X10. and X1, wherein:(i) X8is T, S. N, P, A, or I;(ii) X9is G, N, D, R, V. A, S, or Q;(iii) X10is W, S, C, R, L, or G; and / or(iv) X1 is V. A, S, I, C. G, D. F, L, or T.365. The AAV particle of embodiment 364, wherein [N4] comprises the amino acid sequence of TGWV (SEQ ID NO: 5066).366. The AAV particle of embodiment 364 or embodiment 365, wherein [N4] is present at amino acids 593-596 as numbered according to SEQ ID NO: 981.367. The AAV particle of any one of embodiments 354-366, wherein [N1]-[N2]-[N3]-[N4] comprises the amino acid sequence of TNTQD WHRIAQTGWV (SEQ ID NO: 201).368. An adeno-associated virus (AAV) particle comprising:(i) a viral genome comprising a frataxin (FXN)-encoding sequence: and(ii) an AAV capsid variant comprising an amino acid sequence at least 95% (e.g., at least 95%. at least 96%, at least 97%, at least 98%, or at least 99%) identical to amino acids 203-736 of SEQ ID NO: 981, wherein the AAV capsid variant comprises:T at position 584,D at position 586,W position 587,H at position 588,R at position 589, andI at position 590; wherein the amino acids are numbered according to SEQ ID NO; 981.369. The AAV particle of any one of embodiments 354-368, wherein the AAV capsid variant comprises an amino acid sequence having at least 95% (e.g., at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identity to amino acids 138-736 of SEQ ID NO: 981.370. An adeno-associated virus (AAV) particle comprising:(i) a viral genome comprising a frataxin (FXN)-encoding sequence: and(ii) an AAV capsid variant comprising an amino acid sequence at least 95% (e.g., at least 95%. at least 96%, at least 97%, at least 98%. or at least 99%) identical to amino acids 138-736 of SEQ ID NO: 981, wherein the AAV capsid variant comprises:T at position 584.D at position 586,W position 587,H at position 588,R at position 589, andI at position 590; wherein the amino acids are numbered according to SEQ ID NO: 981.371. The AAV particle of any one of embodiments 354-370, wherein the AAV capsid variant comprises an amino acid sequence having at least 95% (e.g., at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identity’ to SEQ ID NO: 981.372. An adeno-associated virus (AAV) particle comprising:(i) a viral genome comprising a frataxin (FXN)-encoding sequence: and(ii) an AAV capsid variant comprising an amino acid sequence that is at least 95% (e.g., at least 95%, at least 96%. at least 97%, at least 98%, or at least 99%) identical to SEQ ID NO: 981, wherein the AAV capsid variant comprises:T at position 584,D at position 586,W position 587,H at position 588,R at position 589, andI at position 590;wherein the amino acids are numbered according to SEQ ID NO: 981.373. The AAV particle of embodiment 372, wherein the AAV capsid variant comprises:(i) a VP1 protein comprising an amino acid sequence having at least 99% identity to SEQ ID NO: 981;(ii) a VP2 protein comprising an amino acid sequence having at least 99% identity to amino acids 138-736 of SEQ ID NO: 981; and / or(iii) a VP3 protein comprising an amino acid sequence having at least 99% identity to amino acids 203-736 of SEQ ID NO: 981.374. The AAV particle of any one of embodiments 368-373. wherein the AAV capsid variant comprises the amino acid sequence of TQDWHR1 (SEQ ID NO: 941).375. The AAV particle of any one of embodiments 368-374, wherein the AAV capsid variant comprises at least 8, at least 9. or at least 10 consecutive amino acids from the amino acid sequence of TNTQDWHRIAQ (SEQ ID NO: 343).376. The AAV particle of any one of embodiments 368-375, wherein the AAV capsid variant comprises the amino acid sequence of TNTQDWHRIAQ (SEQ ID NO: 343) at amino acids 582-592 as numbered according to SEQ ID NO: 981.377. The AAV particle of any one of embodiments 374-376, wherein the amino acid sequence of TQDWHRI (SEQ ID NO: 941) or TNTQDWHRIAQ (SEQ ID NO: 343) is present in loop VIII, wherein loop VIII comprises amino acids 580-599 as numbered according to SEQ ID NO: 981.378. The AAV particle of any one of embodiments 354-377, wherein the AAV capsid variant comprises:(i) a VP1 protein comprising or consisting of the amino acid sequence of SEQ ID NO: 981;(ii) a VP2 protein comprising or consisting of the amino acid sequence according to positions 138-736 of SEQ ID NO: 981; and / or(iii) a VP3 protein comprising or consisting of the amino acid sequence according to positions 203-736 of SEQ ID NO: 981.379. The AAV particle of any one of embodiments 1-232, 312-318, and 354-378, wherein the FXN- encoding sequence encodes an FXN protein, wherein the FXN protein is not a cynomolgus FXN protein.380. The AAV particle of any one of embodiments 1-232, 312-318. and 354-379, wherein the FXN- encoding sequence encodes a human FXN protein.381. The AAV particle of embodiment 380, wherein the human FXN protein comprises the amino acid sequence of SEQ ID NO: 1825, or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) to SEQ ID NO: 1825, optionally, wherein the FXN protein is a wildtype human FXN protein.382. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380. wherein the FXN- encoding sequence comprises SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%, at least 85%. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) to SEQ ID NO: 1824.383. The AAV particle of any one of embodiments 1-232, 312-318, and 354-382, wherein the viral genome further comprises a promoter operably linked to the FXN-cncoding sequence.384. The AAV particle of embodiment 383. wherein the promoter comprises a human elongation factor la-subunit (EFla) promoter, a cytomegalovirus (CMV) immediate-early enhancer and / or promoter, a chicken [3-actin (CBA) promoter, a CAG promoter, a P glucuronidase (GUSB) promoter, a ubiquitin C (UBC) promoter, a neuron-specific enolase (NSE) promoter, a platelet-derived growth factor (PDGF) promoter, a platelet-derived growth factor B-chain (PDGF- ) promoter, a intercellular adhesion molecule 2 (ICAM-2) promoter, a synapsin (Syn) promoter, a methyl-CpG binding protein 2 (MeCP2) promoter, a Ca2+ / calmodulin-dependent protein kinase II (CaMKII) promoter, a metabotropic glutamate receptor 2 (mGluR2) promoter, a neurofilament light chain (NFL) or neurofilament heavy chain (NFH) promoter, a -globin minigene n^2 promoter, a preproenkephalin (PPE) promoter, a enkephalin (Enk) and excitatory amino acid transporter 2 (EAAT2) promoter, a glial fibril I an acidic protein (GFAP) promoter, a myelin basic protein (MBP) promoter, a cardiovascular promoter (e.g.. aMHC, cTnT. and CMV-MLC2k), a liver promoter (e.g., hAAT, TBG), a skeletal muscle promoter (e.g., desmin, MCK, C512). or a functional fragment or truncation of any one of the foregoing.385. The AAV particle of embodiment 383 or embodiment 384, wherein the promoter is a CMV promoter or CBA promoter, or a functional fragment or truncation thereof.386. The AAV particle of embodiment 385. wherein the promoter is a truncated CBA promoter.387. The AAV particle of embodiment 386. wherein the truncated CBA promoter is 50-400 nucleotides in length, e.g.. 100-332 nucleotides in length.388. The AAV particle of any one of embodiments 385-387. wherein the promoter comprises or consists of the nucleotide sequence of any one of SEQ ID NOs: 1738. 1740, and 1742 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) to any one of SEQ ID NOs: 1738, 1740, and 1742.389. The AAV particle of embodiment 385, wherein the promoter is a truncated CMV promoter.390. The AAV particle of embodiment 389, wherein the truncated CMV promoter is 50-300 nucleotides in length (e.g.. 109 nucleotides in length).391. The AAV particle of embodiment 389 or embodiment 390, wherein the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1750 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) to SEQ ID NO: 1750.392. The AAV particle of any one of embodiments 1-232, 312-318, and 354-391, wherein the viral genome further comprises a miRNA (miR) binding site that modulates expression of the encoded FXN protein in a cell or tissue of the liver.393. The AAV particle of embodiment 392, wherein the viral genome comprises 3 copies of the miR binding site.394. The AAV particle of embodiment 393, wherein the 3 copies of the miR binding site are identical.395. The AAV particle of embodiment 393 or embodiment 394, wherein the 3 copies of the miR binding site are continuous.396. The AAV particle of any one of embodiments 392-395, wherein the miR binding site is amiR122 binding site, optionally wherein: the miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1827 or a sequence having one, two. three, or at most four substitutions relative to SEQ ID NO: 1827; or the 3 copies of miR122 binding sites (miR122 binding site series) comprises the nucleotide sequence of SEQ ID NO: 1826 or a sequence having one, two, three, four, five, six, seven, eight, nine, or at most ten substitutions relative to SEQ ID NO: 1826.397. The AAV particle of any one of embodiments 1-232, 312-318, and 354-396, wherein the viral genome further comprises at least one inverted terminal repeat (ITR) region.398. The AAV particle of embodiment 397, wherein the at least one ITR region comprises an AAV2 ITR.399. The AAV particle of embodiment 397 or embodiment 398, wherein the viral genome comprises a 5' ITR region and a 3’ ITR region.400. The AAV particle of embodiment 399, wherein the 5 ’ ITR region and 3 ’ ITR region are each an AAV2 ITR.401. The AAV particle of embodiment 400. wherein the 5' ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; and / or the 3' ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto.402. The AAV particle of any one of embodiments 1-232, 312-318. and 354-401, wherein the viral genome further comprises an intron / exon region comprising an intron region and / or an exon region.403. The AAV particle of embodiment 402, wherein the intron / exon region comprises: an immediate-early 1 (iel) intron region and / or a human beta-globin (hBglobin) intron region; and / or an iel exon region and / or an hBglobin exon region.404. The AAV particle of embodiment 402 or embodiment 403, wherein the intron region comprises: an iel intron 1 comprising the nucleotide sequence of SEQ ID NO: 1819 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto: and / or a hBglobin intron 2 comprising the nucleotide sequence of SEQ ID NO: 1820 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto.405. The AAV particle of embodiment 404. wherein the exon region comprises: an iel exon region comprising the nucleotide sequence of SEQ ID NO: 1817 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%. at least 96%. at least 97%, at least 98%. or at least 99% identical) thereto; and / oran hBglobin exon region comprising the nucleotide sequence of SEQ ID NO: 1821 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.406. The AAV particle of any one of embodiments 1-232, 312-318, and 354-405, wherein the viral genome further comprises a polyadenylation (poly A) region.407. The AAV particle of embodiment 406. wherein the polyA region comprises a human growth hormone (hGH) polyA region, optionally wherein the polyA region comprises the nucleotide sequence of SEQ ID NO: 1828 or a sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto.408. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1797.409. The AAV particle of any one of embodiments 1-232, 312-318. and 354-380, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1801.410. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1808.411. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1809.412. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380, wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) a FXN -encoding sequence comprising the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g.. at least 80%, at least 85%, at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical) to SEQ ID NO: 1824; and(iv) a 3’ ITR region.413. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380, wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) a FXN -encoding sequence comprising the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%. at least 85%, at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. at least 99%, or 100% identical) to SEQ ID NO: 1824;(iv) at least one miR122 binding site; and(v) a 3’ ITR region.414. The AAV particle of any one of embodiments 1-232, 312-318. and 354-380, wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) an intron and / or exon region;(iv) a FXN-encoding sequence comprising the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g.. at least 80%, at least 85%, at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical) to SEQ ID NO: 1824;(v) at least one miR122 binding site; and(vi) a 3’ ITR region.415. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380, wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) an intron and / or exon region;(iv) a FXN-encoding sequence comprising the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical) to SEQ ID NO: 1824;(v) at least one miR122 binding site;(vi) a poly adenylation (poly A) region; and(vii) a 3’ ITR region.416. The AAV particle of any one of embodiments 1-232, 312-318, and 354-380, wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) an intron and / or exon region;(iv) a FXN-encoding sequence comprising the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%. at least 85%, at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. at least 99%, or 100% identical) to SEQ ID NO: 1824;(v) at least one miR122 binding site;(vi) a polyadenylation (poly A) region;(vii) a filler sequence; and(viii) a 3’ ITR region.417. The AAV particle of embodiment 415 or embodiment 416, wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1742 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto;(v) the at least one miR122 binding site comprises a miR122 binding site series comprising SEQ ID NO: 1826 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; and / or(vii) the 3’ ITR region comprises SEQ ID NO: 1812 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.418. The AAV particle of embodiment 417. wherein the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1841 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.419. The AAV particle of embodiment 415 or embodiment 416, wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1750 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(v) the at least one miR122 binding site comprises a miR122 binding site series comprising SEQ ID NO: 1826 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%. at least 96%. at least 97%, at least 98%. or at least 99% identical) thereto; and / or(vii) the 3" ITR region comprises SEQ ID NO: 1812 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.420. The AAV particle of embodiment 419, wherein the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1840 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.421. The AAV particle of embodiment 415 or embodiment 416, wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1738 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(v) the at least one miR122 binding site comprises a miR122 binding site series comprising SEQ ID NO: 1826 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; and / or(vii) the 3’ ITR region comprises SEQ ID NO: 1812 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.422. The AAV particle of embodiment 421. wherein the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1838 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%. at least 93%. at least 94%, at least 95%. at least 96%, atleast 97%. at least 98%, or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.423. The AAV particle of embodiment 415 or embodiment 416, wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1740 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%. at least 97%, at least 98%. or at least 99% identical) thereto:(v) the at least one miR122 binding site comprises a miR122 binding site series comprising SEQ ID NO: 1826 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or(vii) the 3" ITR region comprises SEQ ID NO: 1812 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto.424. The AAV particle of embodiment 423, wherein the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1839 or a sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.425. The AAV particle of any one of embodiments 1-232, 312-318, and 354-378, wherein the viral genome comprises:(a) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%. at least 92%. at least 93%, at least 94%. at least 95%, at least96%, at least 97%, at least 98%, or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1797;(b) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1801;(c) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1808; or(d) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) to the nucleotide sequence of SEQ ID NO: 1809.426. The AAV particle of any one of embodiments 354-425, wherein the viral genome is single-stranded.427. A cell comprising the AAV particle of any one of embodiments 1-232, 312-318, and 354-426. optionally wherein the cell is a mammalian cell (e.g., an HEK293 cell), an insect cell (e.g., an S19 cell), or a bacterial cell.428. A method of making an AAV particle of any one of embodiments 1-232, 312-318, and 354-426. wherein the method comprises:(i) providing a cell comprising a viral genome comprising a frataxin (FXN)-encoding sequence and a nucleic acid encoding an AAV capsid variant; and(ii) incubating the cell under conditions suitable to encapsulate the viral genome in the AAV capsid variant; thereby making the AAV particle.429. The method of embodiment 428, wherein the viral genome comprises the nucleotide sequence of any one of SEQ ID NOs: 1797. 1801. 1808, and 1809, or a nucleotide sequence at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) to any one of the nucleotide sequences of SEQ ID NOs: 1797, 1801, 1808, and 1809; and wherein the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 981.430. The method of embodiment 428 or embodiment 429, further comprising, prior to step (i), introducing a nucleic acid comprising the viral genome into the cell.431. The method of any one of embodiments 428-430, further comprising, prior to step (i), introducing the nucleic acid encoding the AAV capsid variant into the cell.432. The method of any one of embodiments 428-431. wherein the cell comprises a mammalian cell (e.g., an HEK293 cell), an insect cell (e g., an S19 cell), or a bacterial cell.433. A pharmacal composition comprising the AAV particle of any one of embodiments 1-232, 312- 318, and 354-426 and a pharmaceutically acceptable excipient.434. A method of delivering a frataxin (FXN) protein to a subject, comprising administering to tire subject an effective amount of the pharmaceutical composition of embodiment 433 or the AAV particle of any one of embodiments 1-232. 312-318, and 354-426, thereby delivering the FXN protein.435. The method of embodiment 434, wherein the subject has, has been diagnosed with having, or is at risk of having a disorder associated with FXN deficiency.436. The method of embodiment 435, wherein the disorder associated with FXN deficiency is Friedreich’s Ataxia (FA).437. A method of treating a disorder associated with frataxin (FXN) deficiency in a subject, comprising administering to the subject an effective amount of the pharmaceutical composition of embodiment 433 or the AAV particle of any one of embodiments 1-232, 312-318, and 354-426, thereby treating the disorder.438. The method of embodiment 437, wherein the subject has, has been diagnosed with having, or is at risk of having a disorder associated with FXN deficiency.439. The method of embodiment 437 or embodiment 438, wherein the disorder is Friedreich’s Ataxia (FA).440. The method of any one of embodiments 434-439. wherein the administration results in a increase in the subject’s FXN protein level as compared to baseline, optionally wherein the administration results in a 0.5-3x or 1.5-4x increase in FXN levels as compared to baseline.441. The method of any one of embodiments 437-439, wherein the treatment results in amelioration of at least one symptom of Friedreich’s Ataxia (FA).442. The method of embodiment 441, wherein the at least one symptom of FA comprises impaired sensory functions, impaired motor function (e.g., ataxia and / or involuntary movements), fatigue, chronic pain, seizures, impaired speech, sleep disturbances, metabolic disorders (e.g., diabetes), and / or increased spasticity.443. The method of any one of embodiments 437-442. wherein the treatment stabilizes, slows the progression of, or improves the subject’s FA as determined by the modified Friedreich Ataxia Rating Scale (mFARS). the Scale for the Assessment and Rating of Ataxia (SARA), and / or the International Cooperative Ataxia Rating Scale (1CARS).444. The method of embodiment 443, wherein the treatment slows the subject’s progression of FA as measured by mFARS, SARA, and / or ICARS relative to an individual with the disorder associated with FXN deficiency who has not been administered the pharmaceutical composition or the AAV particle.445. The method of any one of embodiments 434-444, wherein the subject is a human.446. The method of any one of embodiments 434-445, wherein the AAV particle or the pharmaceutical composition is delivered to a cell or tissue of the CNS, optionally wherein the AAV particle or the pharmaceutical composition is delivered via intravenous administration.447. The method of embodiment 446, wherein the cell or tissue of the CNS is a cell or tissue of the amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region).448. The method of any one of embodiments 434-447. further comprising evaluating, e.g.. measuring, the level of FXN expression, e.g., FXN gene, FXN mRNA, and / or FXN protein expression, in the subject, e.g., in a cell, tissue, or fluid, of the subject.449. The method of embodiment 448, wherein the level of FXN protein expression is measured by an cnzvmc-linkcd immunosorbent assay (ELISA), a Western blot, an immunohistochemistry assay, or a frataxin biofluid assay.450. The method of embodiment 448 or embodiment 449, wherein the cell or tissue is a cell or tissue of the central nervous system (CNS).451. The method of embodiment 450, wherein the cell or tissue of the CNS is a cell or tissue of the amygdala, brainstem, caudate, central grey, cerebellum (e.g.. Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen. substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region).452. The method of embodiment 448 or embodiment 449, wherein the cell or tissue is a peripheral cell or tissue.453. The method of embodiment 452, wherein the peripheral cell or tissue is a cell or tissue of the liver, heart, and / or muscle.454. The method of any one of embodiments 434-453, wherein the administration results in an increase in:(i) the level of FXN protein or FXN gene expression in a cell, tissue, (e.g., a cell or tissue of the CNS, e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region), and / or fluid (e.g., CSF and or serum), of the subject relative to baseline and / or relative to the level of FXN protein or FXN gene expression in a cell, tissue, or fluid of an individual with a disorder associated with FXN deficiency who has not been administered the pharmaceutical composition or AAV particle, optionally wherein the level of FXN protein or FXN gene expression is increased by 0.5-3x or 1.5-4x as compared to baseline;(ii) the number and / or level of viral genomes (VG) per cell in a CNS tissue (e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g.. Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneatenucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region)) of the subject relative to the number and / or level of VG per cell in a peripheral tissue of the subject; and / or(iii) the level of FXN activity in a cell, tissue, (e.g., a cell or tissue of the CNS, e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen. substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g.. cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region)), and / or fluid (e.g.., CSF and or serum) of the subject relative to baseline and / or relative to FXN activity in a cell, tissue, or fluid of an individual with a disorder associated with FXN deficiency who has not been administered the pharmaceutical composition or AAV particle.455. The method of any one of embodiments 437-454, further comprising administering to the subject at least one additional therapeutic agent and / or therapy.456. The method of embodiment 455, wherein the at least one additional therapeutic agent and / or therapy comprises an agent and / or therapy for treating the disorder associated with FXN deficiency (e.g., Friedreich’s Ataxia).457. The method of embodiment 456, wherein the at least one additional therapeutic agent and / or therapy comprises omavcloxolonc or idcbcnonc.458. The method of any one of embodiments 437-457, further comprising administering an immunosuppressant to the subject.459. The method of embodiment 458. wherein the immunosuppressant comprises a corticosteroid (e.g., prednisone, prednisolone, methylprednisolone, and / or dexamethasone), rapamycin, mycophenolate mofetil, tacrolimus, rituximab, and / or eculizumab hydroxychloroquine.460. The pharmacal composition of embodiment 433 or the AAV particle of any one of embodiments 1-232. 312-318, and 354-426 for use in a method of treating a disorder according to any one of embodiments 437-459.461. The pharmaceutical composition of embodiment 433 or the AAV particle of any one of embodiments 1-232, 312-318, and 354-426 for use in the treatment of a disorder associated with FXN deficiency in a subject, optionally wherein the disorder is Friedreich’s Ataxia.462. The pharmaceutical composition or tire AAV particle for use of embodiment 461, wherein the subject has, has been diagnosed with having, or is at risk of having Friedreich’s Ataxia.463. Use of an effective amount of the pharmacal composition of embodiment 433 or the AAV particle of any one of embodiments 1-232, 312-318, and 354-426 in the manufacture of a medicament for the treatment of a disorder associated with FXN deficiency in a subject, optionally wherein the disorder is Friedreich’s Ataxia.464. The use of embodiment 463, wherein the subject has. has been diagnosed with having, or is at risk of having Friedreich’s Ataxia.

[0066] The details of various aspects or embodiments of the present disclosure are set forth below. Other features, objects, and advantages of the disclosure will be apparent from the description and the claims. In the description, the singular forms also include the plural unless the context clearly dictates otherwise. Unless defined otherw ise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art in the field of this disclosure. In the case of conflict, the present description will control.BRIEF DESCRIPTION OF THE DRAWINGS

[0067] FIGs. 1A-1D depict frataxin expression and the number of viral genomes per cell in the heart (FIG. 1A); cerebellum (FIG. IB); lumbar and DRG (FIG. 1C); and liver (FIG. ID).

[0068] FIG. 2 shows an exemplary ITR-to-ITR construct encoding FXN.

[0069] FIG. 3A and FIG. 3B show the ratio of human frataxin (huFXN) mRNA expression to cynomolgus frataxin (cyFXN) mRNA expression in the motor cortex (FIG. 3A) and somatosensory cortex (FIG. 3B) following intravenous administration of AAV particles comprising the TTJ-OOlcapsid variant and a single stranded viral genome comprising SEQ ID NO: 1797. at the doses indicated on the X-axis (from left to right: lel3 vg / kg. 3el2 vg / kg, and lel2 vg / kg) in cynomolgus macaques.DETAILED DESCRIPTIONOverview

[0070] Described herein, inter alia, are compositions comprising an AAV capsid variant comprising a sequence encoding a FXN protein, e.g., a human FXN protein. In some embodiments, the present disclosure provides a method for delivering the AAV capsid variant comprising the sequence encoding the FXN protein to a cell or tissue in a subject. In some embodiments, the present disclosure provides amethod for delivering the AAV capsid variant, thereby providing a FXN protein, e.g., a human FXN protein to a cell or tissue in a subject. The AAV capsid variants described herein have enhanced CNS tropism compared to other cells or tissues in the body, e.g.. liver and / or the DRG.

[0071] AAVs have proven to be useful as a biological tool due to their relatively simple structure, their ability to infect a wide range of cells (including quiescent and dividing cells) without integration into the host genome and without replicating, and their relatively benign immunogenic profile. Engineered AAV capsids with improved brain tropism represent an attractive solution to the limitations of CNS delivery. AAV-derived vectors are promising tools for clinical gene transfer because of their non-pathogenic nature, their low immunogenic profile, low rate of integration into the host genome, and long-term transgene expression in non-dividing cells. However, the transduction efficiency of naturally occurring AAVs in certain organs is too low for clinical applications, and capsid neutralization by preexisting neutralizing antibodies may prevent treatment of a large proportion of patients. For these reasons, considerable efforts have been devoted to obtaining capsid variants with enhanced properties. Of many approaches tested so far, significant advances have resulted from directed evolution of AAV capsids using in vitro or in vivo selection of capsid variants created by capsid sequence randomization using either error -prone PCR. shuffling of various parent serotypes, or insertion of fully randomized short peptides at defined positions.

[0072] The genome of the virus may be modified to contain a minimum of components for the assembly of a functional recombinant virus, or viral particle, which is loaded with or engineered to target a particular tissue and express or deliver FXN. The genome of the virus may encode a FXN protein, and the viral particle comprising said genome may be delivered to a target cell, tissue, or organism. In some embodiments, the genome encodes a human FXN protein, e.g., a wildty pe human FXN protein. In some embodiments, the target cell is a CNS cell. In some embodiments, the target tissue is a CNS tissue. The target CNS tissue may be brain tissue. In some embodiments, the CNS tissue comprises amy gdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, and / or temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior oh vary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region).

[0073] Gene therapy presents an alternative approach for treating FA. AAVs are commonly used in gene therapy approaches as a result of a number of advantageous features. Without being bound by theory', it is believed in some embodiments, an AAV particle described herein can be used to administer and / or deliver a gene encoding FXN (e.g., a human FXN) preferentially to the CNS (e.g., the brain or the spinal cord).

[0074] Provided herein are compositions and methods which may provide for improved features compared to prior AAV-mediated approaches, including (i) increased biodistribution throughout the CNS(e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, and / or temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region)), (ii) elevated FXN expression in multiple brain regions (e g., cortex, thalamus, and brain stem); and (iii) preferential biodistribution in the CNS over the liver and / or DRG, of the subject.

[0075] Also provided herein are AAV capsid variants (e.g., AAV9 capsid variants) with improved properties compared to wildtype AAV9, such as (i) increased penetrance through the blood brain barrier following intravenous administration, (ii) wider distribution throughout the multiple brain regions, e.g.. amygdala, brainstem, caudate, central grey, cerebellum (e.g.. Purkinje cell layer and deep cerebellar nuclei), cortex (e.g.. frontal cortex, motor cortex, perirhinal cortex, sensory cortex, and / or temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g.. cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region), (iii) elevated FXN expression in multiple brain regions, (iv) wider distribution in one or more peripheral tissues, e.g., the heart, kidney, muscle (e.g.. quadriceps muscle or skeletal muscle), pancreas, and / or liver, and / or (v) elevated FXN expression in one or more peripheral tissues. In some embodiments, the AAV capsids described herein enhance the deliver}' of FXN to multiple regions of the CNS including, for example, amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region). In some embodiments, the AAV capsids described herein enhance the delivery of FXN to the forebrain. In some embodiments, the AAV capsids described herein enhance the delivery of FXN to the frontal cortex. In some embodiments, the AAV capsids described herein enhance the delivery of FXN to the spinal cord. In some embodiments, the AAV capsids described herein enhance the delivery of FXN to the cerebellum. In some embodiments, the AAV capsids described herein enhance the delivery of FXN to the dentate nucleus. In some embodiments, the AAV capsids described herein enhance the delivery of FXN to the somatosensory cortex. In some embodiments, the AAV capsid variants with enhanced brain tropism described herein are capable of significantly increasing FXN mRNA expression in the brain.

[0076] Thus, the compositions and methods described herein can be used in the treatment of Friedreich’s Ataxia (FA). In some embodiments, the disclosure provides an AAV particle comprising oneof the AAV capsid variants disclosed herein and an AAV viral genome comprising a nucleotide sequence comprising a truncated promoter region and a sequence encoding a FXN protein (e.g., comprising the nucleotide sequence of any one of SEQ ID NOs: 1797, 1801, 1808, and 1809) for use in treating FA.I. CompositionsAdeno-associated viral (AA V) Particles

[0077] AAVs have a genome of about 5.000 nucleotides in length and which contains two open reading frames encoding the proteins responsible for replication (Rep) and the structural protein of the capsid (Cap). The open reading frames are flanked by two Inverted Terminal Repeat (ITR) sequences, which serve as the origin of replication of the viral genome. The wild-type AAV viral genome comprises nucleotide sequences for two open reading frames, one for the four non-structural Rep proteins (Rep78. Rep68, Rep52. Rep40, encoded by Rep genes) and one for the three capsid, or structural, proteins (VP1, VP2, VP3, encoded by capsid genes or Cap genes). The Rep proteins are important for replication and packaging, while the capsid proteins are assembled to create the protein shell of the AAV, or AAV capsid. Alternative splicing and alternate initiation codons and promoters result in the generation of four different Rep proteins from a single open reading frame and the generation of three capsid proteins from a single open reading frame. Though it varies by AAV serotype, as a non-limiting example, for AAV9 / 11U.14 (SEQ ID NO: 123 of US 7,906,111, the contents of which are herein incorporated by reference in their entirety), VP1 refers to amino acids 1-736, VP2 refers to amino acids 138-736, and VP3 refers to amino acids 203-736. In some embodiments, with reference to the amino acid sequence of SEQ ID NO: 981, VP1 comprises amino acids 1-736, VP2 comprises amino acids 138-736, and VP3 comprises amino acids 203-736. In other words, VP1 is the full-length capsid protein sequence, while VP2 and VP3 are shorter components of the whole. As a result, changes in the sequence in the VP3 region are also changes to VP1 and VP2, however, the percent difference as compared to the parent sequence will be greatest for VP3 since it is the shortest sequence of the three. Though described here in relation to the amino acid sequence, the nucleic acid sequence encoding these proteins can be similarly described. Together, the three capsid proteins assemble to create the AAV capsid. Without being bound by theory, the AAV capsid typically comprises a molar ratio of 1 : 1: 10 of VP1:VP2:VP3.

[0078] The AAV particle typically requires a co-helper (e.g.. adenovirus) to undergo productive infection in cells. In the absence of such helper functions, the AAV virions essentially enter host cells but do not integrate into the cells’ genome.

[0079] AAV particles have been investigated for delivery of gene therapeutics because of several unique features. Non-limiting examples of the features include (i) the ability to infect both dividing and non-dividing cells; (ii) a broad host range for infectivity, including human cells; (iii) wild-type AAV has not been associated with any disease and has not been shown to replicate in infected cells; (iv) the lack of cell-mediated immune response against the particle, and (v) the non-integrative nature in a host chromosome thereby reducing potential for long-term genetic alterations. Moreover, infection with AAV particles has minimal influence on changing the pattern of cellular gene expression (Stilwell andSamulski et al., Biotechniques, 2003, 34, 148, the contents of which are herein incorporated by reference in their entirety ).

[0080] Typically, AAV particles for FXN delivery may be recombinant viral particles which are replication defective as they lack sequences encoding functional Rep and Cap proteins within the viral genome. In some cases, the replication defective AAV particles may lack most or all coding sequences and essentially only contain one or two AAV ITR sequences and a nucleic acid sequence encoding a FXN protein (e.g., human FXN protein).

[0081] In some embodiments, the AAV particles of the present disclosure may be introduced into mammalian cells.

[0082] AAV particles may be modified to enhance the efficiency of delivery. Such modified AAV particles of the present disclosure can be packaged efficiently and can be used to successfully infect the target cells at high frequency and with minimal toxicity.

[0083] In other embodiments, AAV particles of the present disclosure may be used to deliver FXN to the central nervous system (see, e.g., U.S. Pat. No. 6,180,613; the contents of which are herein incorporated by reference in their entirety) or to specific tissues of the CNS.

[0084] It is understood that the compositions described herein may have additional conservative or non-essential amino acid substitutions, which do not have a substantial effect on their functions.

[0085] In some embodiments, an AAV capsid variant comprises one or more modifications (e.g.. one or more substitutions) in loop VIII of AAV9, e.g., at one or more amino acids corresponding to positions 580-599 of VP1 of AAV9. In some embodiments, an AAV capsid variant comprises a substitution at one. two, three, four, five, or all of amino acids corresponding to position(s) 584, 586, 587, 588, 589, and / or 590 of the amino acid sequence of SEQ ID NO: 138 or 981. In some embodiments, the term loop (e.g., loop VIII) is used interchangeably herein with the term variable region (e.g., variable region VIII), or VR (e.g., VR-VIII). In some embodiments, loop VIII comprises amino acids corresponding to positions 580- 599 (e.g., the positions of amino acids VATNHQSAQAQAQTGWVQNQ (SEQ ID NO: 5122)) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII is present (is located) at amino acids comprising those corresponding to positions 580-599 (e.g., the positions of amino acids VATNHQSAQAQAQTGWVQNQ (SEQ ID NO: 5122)) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII comprises amino acids corresponding to positions 582-593 (e.g., the positions of amino acids TNHQSAQAQAQT (SEQ ID NO: 5123)) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII comprises amino acids corresponding to positions 587-593 (e.g., the positions of amino acids AQAQAQT (SEQ ID NO: 4687)) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII comprises amino acids corresponding to positions 587-590 (e.g.. the positions of amino acids AQAQ (SEQ ID NO: 5099)) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII is present at amino acids comprising those corresponding to positions 587-590 (e.g., the positions of amino acids AQAQ (SEQ ID NO: 5099)) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII or variable region VIII (VR-VIII) is as described in DiMattia et al. “Structural Insights into the Unique Properties of the Adeno- Associated Virus Serotype 9,” Journal of Virology, 12(86):6947-6958 (the contents of which are hereby incorporated by reference in their entirety), e.g., comprising amino acids corresponding to positions 581- 593 of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII is present at amino acids comprising those corresponding to positions 581-593 of the amino acid sequence of SEQ ID NO: 138.

[0086] The AAV particles and payloads of the disclosure may be delivered to one or more target cells, tissues, organs, or organisms. In some embodiments, the AAV particles demonstrate enhanced tropism for a target cell type, tissue, or organ. As a non-limiting example, the AAV particle may have enhanced tropism for cells and tissues of the central or peripheral nervous systems (CNS and PNS. respectively). In some embodiments, an AAV particle may, in addition, or alternatively, have decreased tropism for a cell-type, tissue or organ.

[0087] In some embodiments, AAV particles are used as a biological tool due to a relatively simple structure, their ability to infect a wide range of cells (including quiescent and dividing cells) without integration into the host genome and without replicating, and their relatively benign immunogenic profile. The genome of the virus may be manipulated to contain a minimum of components for the assembly of a functional recombinant virus, or viral particle, which is loaded with or engineered to target a particular tissue and express or deliver a desired payload.

[0088] In some embodiments, the AAV particle is a recombinant AAV particle. In some embodiments, the wild-type AAV viral genome is a linear, single-stranded DNA (ssDNA) molecule approximately 5.000 nucleotides (nt) in length. In some embodiments, inverted terminal repeats (ITRs) cap the viral genome at both the 5 ’ and the 3 ’ end, providing origins of replication for the viral genome. In some embodiments, an AAV viral genome comprises tw o ITR sequences. In some embodiments, the ITRs have a characteristic T-shaped hairpin structure defined by a self-complementary region (145nt in wild-ty pe AAV) at the 5’ and 3’ ends of the ssDNA which form an energetically stable double stranded region. In some embodiments, the double stranded hairpin structures comprise multiple functions including, but not limited to, acting as an origin for DNA replication by functioning as primers for the endogenous DNA polymerase complex of the host viral replication cell.

[0089] AAV particles of the present disclosure may be produced recombinantly and may be based on AAV reference sequences. In addition to single-stranded AAV viral genomes (e.g., ssAAVs), the present disclosure also provides for self-complementary AAV (scAAV) viral genomes. scAAV viral genomes contain DNA strands that anneal together to form double-stranded DNA. By skipping second strand synthesis, scAAVs allow for rapid expression in the transduced cell. In some embodiments, the AAV particle of the present disclosure is an scAAV. In some embodiments, the AAV particle of the present disclosure is an ssAAV.

[0090] Methods for producing and / or modifying AAV particles are disclosed in the art such as pseudotyped AAV particles (PCT Patent Publication Nos. W0200028004; WQ200123001;W02004112727; W02005005610; and W02005072364, the contents of each of which are incorporated herein by reference in their entirety).

[0091] As described herein, the AAV particles of the disclosure comprising an AAV capsid variant, and a viral genome, have enhanced tropism for a cell-type or a tissue, e.g., a CNS cell-type, region, or tissue.AAV Capsid Variants

[0092] Disclosed herein are AAV particles comprising an AAV capsid variant comprising one or more modifications (e.g., comprising one or more substitutions relative to a wildtype AAV capsid) for enhanced or improved transduction of a target tissue (e.g., cells, regions, and / or tissues of the CNS and / or PNS). In some embodiments, the peptide (e.g.. comprising one or more substitutions relative to a wildtype AAV capsid) is present in VP1, VP2. and / or VP3 proteins of the AAV capsid variant. In some embodiments, the modification (e.g., comprising one or more substitutions relative to a wildtype AAV capsid) is present in VP1. VP2, and VP3 proteins of the AAV capsid variant.

[0093] In some embodiments, the modification (e.g.. comprising the one or more substitutions relative to a wildtype AAV capsid) is in loop VIII. In some embodiments, the AAV capsid variant is an AAV9 capsid variant.

[0094] In some embodiments, the one or more substitutions in the AAV capsid may increase distribution of an AAV particle to a cell, region, or tissue of the CNS. The cell of the CNS may be, but is not limited to, neurons (e.g., excitatory, inhibitory, motor, sensory, autonomic, sympathetic, parasympathetic, Purkinje, Betz, etc.), glial cells (e.g., microglia, astrocytes, oligodendrocytes) and / or supporting cells of the brain such as immune cells (e.g., T cells). The tissue of the CNS may be, but is not limited to, amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, and / or temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary' complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g.. cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region).

[0095] In some embodiments, the one or more substitutions may increase distribution of an AAV particle to a cell, region, or tissue of the CNS. In some embodiments, the one or more substitutions may decrease distribution of an AAV particle to the DRG.[ 0961 In some embodiments, the one or more substitutions may increase distribution of an AAV particle to the CNS (e.g.. the cortex) after intravenous administration. In some embodiments, the one or more substitutions may increase distribution of an AAV particle to the CNS (e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, and / or temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus. gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventralpalladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region) following focused ultrasound (FUS), e.g., coupled with the intravenous administration of microbubbles (FUS-MB), or MRI-guided FUS coupled with intravenous administration.

[0097] hi some embodiments, the one or more substitutions may increase distribution of an AAV particle to the PNS (e.g., DRG) after intravenous administration. In some embodiments, the one or more substitutions may increase distribution of an AAV particle to non-DRG cells of the PNS following focused ultrasound (FUS), e.g.. coupled with the intravenous administration of microbubbles (FUS-MB). or MRI-guided FUS coupled with intravenous administration. In some embodiments, the one or more substitutions may decrease distribution of an AAV particle to the DRG following focused ultrasound (FUS), e.g., coupled with tire intravenous administration of microbubbles (FUS-MB), or MRI-guided FU S coupled with intravenous administration.

[0098] In some embodiments, the one or more modifications, e.g., substitutions, may increase distribution of an AAV particle to a cell, region, or tissue of a heart, e.g., a heart atrium or a heart ventricle. In some embodiments, the one or more substitutions may increase distribution of an AAV particle to a heart cell, region, or tissue after intravenous administration.

[0099] In some embodiments, the one or more modifications, e.g., substitutions, may increase distribution of an AAV particle to a cell, region, or tissue of a muscle. In some embodiments, the muscle is a heart muscle (e.g., a heart atrium or a heart ventricle) or a quadriceps muscle. In some embodiments, the muscle is a skeletal muscle. In some embodiments, the one or more substitutions may increase distribution of an AAV particle to a muscle cell, region, or tissue after intravenous administration.

[0100] In some embodiments, the one or more modifications, e.g., substitutions, may increase distribution an AAV particle to a cell, region, or tissue of the kidney. In some embodiments, the one or more substitutions may increase distribution an AAV particle to a cell, region, or tissue of the pancreas.

[0101] In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) a sequence as set forth in Table 1. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) a sequence as set forth in Table 2A. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) a sequence as set forth in Table 2B (e.g., a sequence of any one of SEQ ID NOs: 201, 205-209, 211-214, 216, 219, 220, 230, 232, 237, 238, 255, 262-265, 274, 283, 286, 290, 291, 293. 301, 306, 307, 308, 309, 314. and 336). In some embodiments, the AAV capsid variant comprises (e.g.. in loop VIII) a sequence set forth in Table 9. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) a sequence as set forth in Table 24. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) a sequence as set forth in Table 25. In some embodiments, the AAV capsid variant is an AAV9 capsid variant.Table 1. Exemplary SequencesTable 2A. Exemplary SequencesTable 2B. Exemplary Sequences

[0102] In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence having the formula [N1]-[N2]-[N3] (SEQ ID NO: 4681), wherein [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682) and wherein [Nl] comprises amino acids Xi. X2. X3, and X4, wherein X4 is Q, K. E, S, P. R, N, H. or a conservative substitution thereof and / or [N3] comprises Xs, X6, and X?, wherein X5is I. V, T, M, S, N. L, F, or a conservative substitution thereof. In some embodiments, [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682), [Nl] comprises Xi, X2, X3, and X4. wherein X , is Q, K, E, S, P, R, N, or H. and / or [N3] comprises X5, X6, and X?, wherein X5is I, V, T, M, S. N, L, or F. In some embodiments, X4of [Nl] is Q. In some embodiments, X, of [Nl] is K. In some embodiments, X5of [N3] is I. In some embodiments, Xi of [Nl] is T, S, R, A, I, C, N, K, L, or Q. In some embodiments, X2of [Nl] is N, T, G, V, S, Y, K, I, H, D, or F. In some embodiments, X3of [Nl] is T, N, K, D, I, S. P, A, Y, E, V, L, M, R, H, Q, or C. In some embodiments, [Nl] is or comprises TNTQ (SEQ ID NO: 4688). In some embodiments, [Nl] is or comprises TNTK (SEQ ID NO: 4689). In some embodiments, [N1]-[N2] is or comprises TNTQDWHR (SEQ ID NO: 4898). In some embodiments, [N1]-[N2] is or comprises TNTKDWHR (SEQ ID NO: 4899). In some embodiments, Xg of [N3] is A, Y, P, N, S, T, G, E, V, W, F, or Q. In some embodiments, X? of [N3] is Q, G, N, K, H, R. E, L, P, or M. In some embodiments, [N3] is or comprises IAQ. In some embodiments, [N2]-[N3] is or comprises DWHRIAQ (SEQ ID NO: 5027). In some embodiments, [N1]-[N2]-[N3] is or comprises TNTQDWHRIAQ (SEQ ID NO: 343). In some embodiments, [N1]-[N2]-[N3] is or comprises TNTKDWHRIAQ (SEQ ID NO: 344).

[0103] In some embodiments, the amino acid sequence having the formula [N1]-[N2]-[N3] further comprises [N4], wherein [N4] comprises amino acids X8, X9, X10, and Xu, wherein X8is T, S, N, P, A. orI; X9is G, N, D, R, V, A, S, or Q; Xio is W, S, C, R, L, or G; and / or Xnis V, A, S, I, C, G, D, F, L, or T. In some embodiments, [N4] is or comprises TGWV (SEQ ID NO: 5066). In some embodiments, [Nl]- [N2]-[N3]-[N4] is or comprises any one of SEQ ID NOs: 201-245, 247-250, 253-255, 257-265, 268-274, 276-286, 288, 290-297, 299-303, 305-309, 311, 313-319, 323-328, 330-337, 339-342, 539-542, 544, 546, 547, 549-557, 559-589, 592, 593. 595, 596, 598, 599, 601-608, 610-614, 616-622, 625, 628, 630, 631, 633, 636, 638. 639-646, 649, 651-657, 667, 669, 670, 672, 673, 679-683, 685-690, 692, 693. 695, 697, 699-701, 703-705. 708-710, 712-717. 719-723, 728-731, 733-738, 740. and 742. In some embodiments, [N1]-[N2]-[N3]-[N4] is or comprises TNTQDWHRIAQTGWV (SEQ ID NO: 201). In some embodiments, [N1]-[N2]-[N3]-[N4] is or comprises TNTKDWHRIAQTGWV (SEQ ID NO: 202).

[0104] In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence having the formula [N1]-[N2]-[N3] (SEQ ID NO: 4683), wherein [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682) and wherein [Nl] comprises amino acids X X2, X3. and X4. wherein X4is Q. P, or a conservative substitution thereof; and / or [N3] comprises amino acids X5. X6. and X7, wherein X5is I. V, or a conservative substitution thereof. In some embodiments, [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682); [Nl] comprises amino acids Xi, X2. X3. and X4, wherein X4is Q or P; and / or [N3] comprises amino acids X3, Xe, and X?, wherein X3is I or V. In some embodiments, X4of [Nl] is Q. In some embodiments, X5of [N3] is I. In some embodiments. X5of [N3] is V. In some embodiments, Xi of [Nl] is T or S. In some embodiments, X2of [Nl] is N. T, G, S. I. or V. In some embodiments, X3of [Nl] is T, N, I, S, A, V. or L. In some embodiments, [Nl] is or comprises TNTQ (SEQ ID NO: 4688). In some embodiments, [N1]-[N2] is or comprises TNTQDWHR (SEQ ID NO: 4898). In some embodiments, Xg of [N3] is A, P, S, Y, or N. In some embodiments. X7of [N3] is Q, G, or N. In some embodiments, [N3] is or comprises IAQ. In some embodiments, [N2]-[N3] is or comprises DWHRIAQ (SEQ ID NO: 5027). In some embodiments, [N1]-[N2]-[N3] is or comprises TNTQDWHRIAQ (SEQ ID NO: 343). In some embodiments, the amino acid sequence having the formula [N1]-[N2]-[N3] further comprises [N4], wherein [N4] comprises amino acids X8, X9, Xio, and Xn, wherein X10 is W. In some embodiments, Xxof [N4] is T, S, or N. In some embodiments, X7of [N4] is G or N. In some embodiments, X1 of [N4] is V, A, I, or S. In some embodiments, [N4] is or comprises TGWV (SEQ ID NO: 5066). In some embodiments, [N1]-[N2]-[N3]-[N4] is or comprises any one of SEQ ID NOs: 201, 205-209, 211-214, 216, 219, 220, 230, 232. 237, 238, 255, 262-265, 274, 283, 286, 290, 291, 293, 301, 306, 307. 308, 309, 314, and 336. In some embodiments, [N1]-[N2]-[N3]-[N4] is or comprises TNTQDWHRIAQTGWV (SEQ ID NO: 201).

[0105] In some embodiments, [N1]-[N2]-[N3] is present in loop VIII of the AAV capsid variant. In some embodiments, [N4] is present in loop VIII of the AAV capsid variant. In some embodiments. [Nl]- [N2]-[N3]-[N4] is present in loop VIII of the AAV capsid variant. In some embodiments, loop VIII is present at amino acids comprising those corresponding to positions 581-593 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, loop VIII is present at amino acidscomprising those corresponding to positions 580-599 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981.

[0106] In some embodiments, [Nl] is present at amino acids corresponding to positions 582-585 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, Xi of [Nl] is present at an amino acid corresponding to position 582 of the amino acid sequence of SEQ ID NO: 138 or 981, X2of [Nl] is present at an amino acid corresponding to position 583 of the amino acid sequence of SEQ ID NO: 138 or 981, X3of [Nl] is present at an amino acid corresponding to position 584 of the amino acid sequence of SEQ ID NO: 138 or 981, and X4of [Nl] is present at an amino acid corresponding to position 585 of the amino acid sequence of SEQ ID NO: 138 or 981. In some embodiments. [Nl] replaces amino acids corresponding to positions 582-585 (e.g., T582, N583, H584. and Q585) of the amino acid sequence of SEQ ID NO: 138.

[0107] In some embodiments, [N2] is present at amino acids corresponding to positions 586-589 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, [N2] replaces amino acids corresponding to positions 586-589 of the amino acid sequence of SEQ ID NO: 138 (e.g., S586, A587. Q588. and A589 may be replaced with D586, W587. H588, and R589).

[0108] In some embodiments. [N1]-[N2] is present at amino acids corresponding to positions 582- 589 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, [Nl]- [N2] replaces amino acids corresponding to positions 582-589 of the amino acid sequence of SEQ ID NO: 138 (e.g., T582, N583. H584, Q585, S586, A587, Q588. and A589 may be replaced with T582, N583. T584. Q585, D586, W587. H588, and R589).

[0109] In some embodiments, [N3] is present at amino acids corresponding to positions 590-592 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, X5of [N3] is present at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 138 or 981, X6of [N3] is present at an amino acid corresponding to position 591 of the amino acid sequence of SEQ ID NO: 138 or 981, and X7of [N3] is present at an amino acid corresponding to position 592 of die ammo acid sequence of SEQ ID NO: 138 or 981. In some embodiments, [N3] replaces amino acids corresponding to positions 590-592 (e.g., 1590, A591, and Q592) of the amino acid sequence of SEQ ID NO: 138.

[0110] hi some embodiments, [N2]-[N3] is present at amino acids corresponding to positions 586- 592 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, [N2]- [N3] replaces amino acids corresponding to positions 586-592 of the amino acid sequence of SEQ ID NO: 138 (e.g.. S586. A587, Q588, A589, Q590, A591, and Q592 may be replaced with D586, W587, H588, R589, 1590. A591, and Q592).[oni] In some embodiments, [N1]-[N2]-[N3] is present at amino acids corresponding to positions 582-592 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, [N1]-[N2]-[N3] replaces amino acids corresponding to positions 582-592 of the amino acid sequence ofSEQ ID NO: 138 (e.g., T582, N583, H584, Q585, S586, A587, Q588, A589, Q590, A591, and Q592 may be replaced with T582, N583, T584, Q585, D586, W587, H588, R589, 1590, A591, and Q592).

[0112] In some embodiments, [N4] is present at amino acids corresponding to positions 593-596 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, Xg of [N4] is present at an amino acid corresponding to position 593 of the amino acid sequence of SEQ ID NO: 138 or 981, X9of [N4] is present at an amino acid corresponding to position 594 of the amino acid sequence of SEQ ID NO: 138 or 981, Xio of [N4] is present at an amino acid corresponding to position 595 of the amino acid sequence of SEQ ID NO: 138 or 981, and Xu of [N4] is present at an amino acid corresponding to position 596 of the amino acid sequence of SEQ ID NO: 138 or 981. In some embodiments. [N4] replaces amino acids corresponding to positions 593-596 (e.g., T593, G594, W595, and V596) of the amino acid sequence of SEQ ID NO: 138.

[0113] In some embodiments, [N2]-[N3]-[N4] is present at amino acids corresponding to positions 586-596 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, [N2]-[N3]-[N4] replaces amino acids corresponding to positions 586-596 of the amino acid sequence of SEQ ID NO: 138 (e.g., S586, A587. Q588, A589, Q590, A591. Q592. T593. G594, W595. and V596 may be replaced with D586, W587, H588. R589. 1590. A591. Q592, T593, G594, W595. and V596).

[0114] In some embodiments. [N 1]-[N2]-[N3]-[N4] is present at amino acids corresponding to positions 582-596 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, [N1]-[N2]-[N3]-[N4] replaces amino acids corresponding to positions 582-596 of the amino acid sequence of SEQ ID NO: 138 (e.g., T582, N583, H584, Q585. S586. A587, Q588, A589, Q590. A591, Q592, T593, G594, W595, and V596 may be replaced with T582, N583, T584, Q585, D586, W587, H588, R589, 1590, A591, Q592. T593, G594, W595, and V596).

[0115] In some embodiments, [N2] is present immediately subsequent to [Nl], In some embodiments, [N3] is present immediately subsequent to [N2], In some embodiments, [N4] is present immediately subsequent to [N3] . In some embodiments, loop VIII of the AAV capsid variant comprises an ammo acid sequence comprising, from N-terminus to C-tenninus, [N1]-[N2]-[N3], In some embodiments, loop VIII of the AAV capsid variant comprises an amino acid sequence comprising, from N-terminus to C-terminus, [N1]-[N2]-[N3]-[N4],

[0116] hi some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence comprising at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, or at least 14 consecutive amino acids from any one of the sequences provided in Table 1, 2A, 2B, 9. 24, 25, or 26. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence comprising at least 3. at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10. at least 11, at least 12, at least 13. or at least 14 consecutive amino acids from any one of SEQ ID NOs: 201. 205-209, 211-214. 216, 219. 220, 230, 232. 237, 238, 255. 262-265, 274, 283, 286. 290, 291, 293. 301, 306. 307, 308, 309. 314, and 336.

[0117] In some embodiments, the at least 3 consecutive amino acids comprise TQD. In some embodiments, the at least 4 consecutive amino acids comprise TQDW (SEQ ID NO: 4684). In some embodiments, tire at least 5 consecutive amino acids comprise TQDWH (SEQ ID NO: 4685). In some embodiments, the at least 6 consecutive amino acids comprise TQDWHR (SEQ ID NO: 4686). In some embodiments, the at least 7 consecutive amino acids comprise TQDWHRI (SEQ ID NO: 941).

[0118] In some embodiments, the at least 3 consecutive amino acids comprise TNT. In some embodiments, the at least 4 consecutive amino acids comprise TNTQ (SEQ ID NO: 4688). In some embodiments, the at least 5 consecutive amino acids comprise TNTQD (SEQ ID NO: 5119). In some embodiments, the at least 6 consecutive amino acids comprise TNTQDW (SEQ ID NO: 5120). In some embodiments, the at least 7 consecutive amino acids comprise TNTQDWH (SEQ ID NO: 5121). In some embodiments, the at least 8 consecutive amino acids comprise TNTQDWHR (SEQ ID NO: 4898). In some embodiments, the at least 9 consecutive amino acids comprise TNTQDWHR1 (SEQ ID NO: 746).

[0119] In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence comprising at least one. at least two. or at least three modifications, but no more than four modifications, relative to the amino acid sequence of any one of the sequences provided in Table 1. 2A. 2B, 9, 24, 25, or 26. In some embodiments, the AAV capsid variant comprises (e g., in loop VIII) an amino acid sequence comprising at least one, at least two, or at least three substitutions, but no more than four substitutions, relative to the amino acid sequence of any one of the sequences provided in Table 1, 2A, 2B, 9, 24, 25, or 26. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence comprising at least one, at least two, or at least three modifications, but no more than four modifications, relative to the amino acid sequence of any one of SEQ ID NOs: 201, 205-209, 211-214, 216, 219. 220, 230, 232, 237, 238, 255, 262-265, 274, 283, 286, 290, 291, 293, 301, 306, 307.308, 309, 314, and 336. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence comprising at least one, at least two, or at least three substitutions, but no more than four substitutions, relative to the amino acid sequence of any one of SEQ ID NOs: 201, 205-209, 211- 214, 216, 219, 220, 230, 232, 237, 238, 255, 262-265, 274, 283, 286, 290, 291, 293, 301, 306, 307, 308,309, 314, and 336.

[0120] In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence comprising at least one. at least two. or at least three modifications, but no more than four modifications, relative to the amino acid sequence of TQDWHRI (SEQ ID NO: 941). In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence comprising at least one, at least two, or at least three substitutions, but no more than four substitutions, relative to the amino acid sequence of TQDWHRI (SEQ ID NO: 941).

[0121] In some embodiments, the AAV capsid variant comprises the amino acid sequence of any one of the sequences provided in Table 1. 2A. 2B. 9. 24. 25, or 26. In some embodiments, the AAV capsid variant comprises the amino acid sequence of any one of SEQ ID NOs: 201, 205-209. 211-214, 216, 219.220, 230, 232, 237, 238, 255, 262-265, 274, 283, 286, 290, 291, 293, 301, 306, 307, 308, 309, 314, and 336.

[0122] In some embodiments, the amino acid sequence is present in loop VIII. In some embodiments, loop VIII comprises amino acids corresponding to positions 581-593 of the amino acid sequence of SEQ ID NO: 138. In some embodiments, loop VIII comprises amino acids corresponding to positions 580-599 of the amino acid sequence of to SEQ ID NO: 138. In some embodiments, loop VIII is present (is located) at amino acids comprising those corresponding to positions 580-599 (e.g., the positions of amino acids VATNHQSAQAQAQTGWVQNQ (SEQ ID NO: 5122)) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the amino acid sequence replaces 1. 2. 3, 4, 5, 6, 7. 8. 9, 10. 11, 12, 13, 14, or all of amino acids corresponding to position(s) 582 (e.g., T582). 583 (e.g., N583), 584 (e.g., H584). 585 (e.g., Q585), 586 (e.g.. S586), 587 (e.g., A587). 588 (e.g., Q588), 589 (e.g.. A589), 590 (e.g., Q590). 591 (e.g., A591), 592 (e.g.. Q592), 593 (e.g., T593). 594 (e.g., G594), 595 (e.g.. W595). and / or 596 (e.g.. V596) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the amino acid sequence is present at 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or all of amino acids corresponding to position(s) 582, 583. 584, 585, 586. 587, 588, 589. 590, 591. 592, 593, 594. 595, and / or 596 of the amino acid sequence of SEQ ID NO: 981. In some embodiments, the AAV capsid variant comprises one or more substitutions at amino acids corresponding to position(s) 582 (e.g., T582). 583 (e.g., N583). 584 (e.g., H584), 585 (e.g.. Q585), 586 (e.g., S586). 587 (e.g., A587), 588 (e.g.. Q588), 589 (e.g., A589). 590 (e.g., Q590), 591 (e.g.. A591), 592 (e.g., Q592), 593 (e.g., T593), 594 (e.g., G594), 595 (e.g., W595), and / or 596 (e.g., V596) of the amino acid sequence of SEQ ID NO: 138.

[0123] In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence encoded by a nucleotide sequence described herein, e.g., a nucleotide sequence of Table 2A. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence encoded by a nucleotide sequence comprising at least one, at least tw o. at least three, at least four, at least five, at least six, or at least seven modifications, but no more than ten modifications, relative to the nucleotide sequence of SEQ ID NO: 942. In some embodiments, die AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence encoded by a nucleotide sequence comprising at least one, at least tw o. at least three, at least four, at least five, at least six, or at least seven different substitutions, but not more than ten substitutions, relative to the nucleotide sequence of SEQ ID NO: 942. In some embodiments, the AAV capsid variant comprises (e.g., in loop VIII) an amino acid sequence encoded by the nucleotide sequence of SEQ ID NO: 942, or a nucleotide sequence substantially identical (e.g., having at least 70%, at least 75%, at least 80%, at least 85%. at least 90%, at least 92%, at least 95%. at least 97%, at least 98%, or at least 99% sequence identity) thereto.

[0124] In some embodiments, the nucleotide sequence encoding an AAV capsid variant described herein, or a portion thereof that is modified relative to a wildtype AAV capsid (e.g.. comprising one or more substitutions relative to a wildtype AAV capsid), comprises a nucleotide sequence described herein, e.g., as described in Table 2A. In some embodiments, the nucleotide sequence encoding an AAV capsidvariant described herein, or a portion thereof that is modified relative to a wildtype AAV capsid (e.g., comprising one or more substitutions relative to a wildtype AAV capsid), is codon optimized. In some embodiments, the nucleotide sequence is an isolated nucleotide sequence. In some embodiments, the nucleotide sequence is a recombinant nucleotide sequence.

[0125] In some embodiments, the nucleotide sequence encoding an AAV capsid variant described herein, or a portion thereof that is modified relative to a wildtype AAV capsid (e.g., comprising one or more substitutions relative to a wildtype AAV capsid), comprises the nucleotide sequence of SEQ ID NO: 942, or a nucleotide sequence comprising at least one. at least two. at least three, at least four, at least five, at least six, or at least seven modifications, but no more than ten modifications, relative to the nucleotide sequence of SEQ ID NO: 942. In some embodiments, the nucleotide sequence comprises a nucleotide sequence comprising at least one, at least two, at least three, at least four, at least five, at least six. or at least seven substitutions, but no more than ten substitutions, relative to the nucleotide sequence of SEQ ID NO: 942. In some embodiments, the nucleotide sequence comprises the nucleotide sequence of SEQ ID NO: 942, or a nucleotide sequence substantially identical (e.g., having at least 70%, at least 75%, at least 80%, at least 85%. at least 90%, at least 92%. at least 95%, at least 97%, at least 98%. or at least 99% sequence identity) thereto.

[0126] In some embodiments, the AAV capsid variant further comprises an amino acid other than A at a position corresponding to position 581 of the amino acid sequence of SEQ ID NO: 138 or 981. In some embodiments, the AAV capsid variant further comprises the amino acid T at a position corresponding to position 581 of the amino acid sequence of SEQ ID NO: 138 or 981. In some embodiments, the AAV capsid variant further comprises the amino acid V at a position corresponding to position 581 of the amino acid sequence of SEQ ID NO: 138 or 981. In some embodiments, the AAV capsid variant comprises the substitution A581T or A581V, wherein the substitution is at a position that corresponds to position 581 of the amino acid sequence of SEQ ID NO: 138 or 981.

[0127] In some embodiments, an AAV capsid variant described herein comprises one, two, three, four, five, or all of an amino acid other than H at a position corresponding to position 584 (e g., comprises T at an amino acid corresponding to position 584) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than S at a position corresponding to position 586 (e.g., comprises D at an amino acid corresponding to position 586) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than A at a position corresponding to position 587 (e.g., comprises W at an amino acid corresponding to position 587) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than Q at a position corresponding to position 588 (e.g., comprises H at an amino acid corresponding to position 588) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than A at a position corresponding to position 589 (e.g.. comprises R at an amino acid corresponding to position 589) of the amino acid sequence of SEQ ID NO: 138; and / or an amino acid other than Q at a position corresponding to position 590 (e.g.. comprises I at an amino acid corresponding to position 590) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant comprises an amino acidother than H at a position corresponding to position 584 (e.g., comprises T at an amino acid corresponding to position 584) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than S at a position corresponding to position 586 (e.g.. comprises D at an amino acid corresponding to position 586) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than A at a position corresponding to position 587 (e.g.. comprises W at an amino acid corresponding to position 587) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than Q at a position corresponding to position 588 (e.g. comprises H at an amino acid corresponding to position 588) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than A at a position corresponding to position 589 (e.g., comprises R at an amino acid corresponding to position 589) of the amino acid sequence of SEQ ID NO: 138; and an amino acid other than Q at a position corresponding to position 590 (e.g., comprises I at an amino acid corresponding to position 590) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, an AAV capsid variant described herein comprises the amino acid T at a position corresponding to position 584 of the amino acid sequence of SEQ ID NO: 138 or 981. amino acid D at a position corresponding to position 586 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid W at a position corresponding to position 587 of the amino acid sequence of SEQ ID NO: 138 or 981. amino acid H at a position corresponding to position 588 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid R at a position corresponding to position 589 of the amino acid sequence of SEQ ID NO: 138 or 981, and amino acid I at a position corresponding to position 590 of the amino acid sequence of SEQ ID NO: 138 or 981.

[0128] In some embodiments, an AAV capsid variant described herein comprises one, two, three, four, five, or all of the amino acid T at a position corresponding to position 584 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid D at a position corresponding to position 586 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid W at a position corresponding to position 587 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid H at a position corresponding to position 588 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid R at a position corresponding to position 589 of the amino acid sequence of SEQ ID NO: 138 or 981, and / or amino acid I at a position corresponding to position 590 of the amino acid sequence of SEQ ID NO: 138 or 981. In some embodiments, the AAV capsid variant comprises the amino acid T at a position corresponding to position 584 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid D at a position corresponding to position 586 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid W at a position corresponding to position 587 of the amino acid sequence of SEQ ID NO: 138 or 981. amino acid H at a position corresponding to position 588 of the amino acid sequence of SEQ ID NO: 138 or 981, amino acid R at a position corresponding to position 589 of the amino acid sequence of SEQ ID NO: 138 or 981, and amino acid I at a position corresponding to position 590 of the amino acid sequence of SEQ ID NO: 138 or 981.

[0129] In some embodiments, an AAV capsid variant described herein comprises one. two, three, four, five, or all of the substitutions H584T. S586D. A587W, Q588H, A589R, and / or Q590I, wherein thesubstitution(s) is / are at position(s) that correspond to position(s) 584, 586, 587, 588, 589, and / or 590 of die amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant comprises the substitutions H584T, S586D, A587W, Q588H, A589R, and Q590I, wherein the substitution(s) is / are at position(s) tiiat correspond to position(s) 584, 586, 587, 588. 589, and / or 590 of the amino acid sequence of SEQ ID NO: 138 or 981.

[0130] In some embodiments, an AAV capsid variant described herein comprises the amino acid Q at an amino acid corresponding to position 585 of the amino acid sequence of SEQ ID NO: 138 or 981.

[0131] In some embodiments, an AAV capsid variant described herein comprises an amino acid other than Q at an amino acid corresponding to position 585 of the amino acid sequence of SEQ ID NO: 138. In some embodiments, an AAV capsid variant described herein comprises the amino acid K at an amino acid corresponding to position 585 of the amino acid sequence of SEQ ID NO: 138.

[0132] In some embodiments, an AAV capsid variant described herein comprises an amino acid other than Q at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant comprises the amino acid I at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant comprises the amino acid V at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 138.

[0133] In some embodiments, an AAV capsid variant described herein comprises the amino acid sequence of TQDWHRI (SEQ ID NO: 941). wherein TQDWHRI (SEQ ID NO: 941) is present in the AAV capsid variant at amino acids corresponding to positions 584-590 of the amino acid sequence of SEQ ID NO: 138 or SEQ ID NO: 981. In some embodiments, TQDWHRI (SEQ ID NO: 941) is present at amino acids corresponding to positions 584-590 of the amino acid sequence of SEQ ID NO: 138 (e.g., H584. S586. A587, Q588, A589, and Q590 may be replaced with T584, D586, W587, H588, R589, and 1590).

[0134] In some embodiments, an AAV capsid variant described herein comprises the amino acid W at an amino acid corresponding to position 595 of the amino acid sequence of SEQ ID NO: 138 or 981.

[0135] In some embodiments, the AAV capsid variant further comprises a substitution corresponding to amino acid K449 (e.g., K449R) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant further comprises an amino acid other than K at a position corresponding to position 449 (e.g.. comprises an R at a position corresponding to position 449) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant comprises an R at amino acid corresponding to position 449 of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant further comprises a modification in loop I, II, IV. and / or VI.

[0136] In some embodiments, the AAV capsid variant further comprises an amino acid sequence comprising at least one, at least two, or at least three modifications, but not more than 30, not more than 20, or not more than 10 modifications, relative to the amino acid sequence of SEQ ID NO: 138. In some embodiments, the amino acid sequence does not comprise more than 10 modifications. In someembodiments, the AAV capsid variant further comprises an amino acid sequence comprising at least one, at least two, or at least three, but not more than 30, not more than 20, or not more than 10 amino acids that differ from the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant further comprises the amino acid sequence of SEQ ID NO: 138. or an amino acid sequence with at least 70% (e.g., at least 70%. at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity thereto.

[0137] In some embodiments, the AAV capsid variant comprises (a) a VP1 protein comprising the amino acid sequence of SEQ ID NO: 981 (i.e., comprising amino acids 1-736 of SEQ ID NO: 981); (b) a VP2 protein comprising amino acids 138-736 of SEQ ID NO: 981; (c) a VP3 protein comprising amino acids 203-736 of SEQ ID NO: 981: or (d) an amino acid sequence with at least 70% (e.g., at least 70%. at least 75%, at least 80%, at least 85%. at least 90%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99%) sequence identity to any one of the amino acid sequences in (a)-(c). an amino acid sequence comprising at least one. at least two. or at least three substitutions, but not more than 30, not more than 20, or not more than 10 substitutions relative to any one of the amino acid sequences in (a)-(c), or an amino acid sequence comprising at least one. at least two. or at least three modifications, but not more than 30, not more than 20. or not more than 10 such modifications relative to any one of the amino acid sequences in (a)-(c).

[0138] In some embodiments, the AAV capsid variant comprises (a) a VP1 protein comprising an amino acid sequence that is at least 90% (e.g., at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 981; (b) a VP2 protein comprising an amino acid sequence that is at least 90% (e.g., at least 90%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99%) identical to amino acids 138-736 of SEQ ID NO: 981; and / or (c) a VP3 protein comprising an amino acid sequence that is at least 90% (e.g., at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to amino acids 203-736 of SEQ ID NO: 981, wherein the AAV capsid variant comprises the amino acid sequence of TQDWHRI (SEQ ID NO: 941) or a sequence comprising one, two, or three but not more than three substitutions relative to the amino acid sequence of TQDWHRI (SEQ ID NO: 941). In some embodiments, the AAV capsid variant comprises the amino acid sequence comprising one, tw o. or three but not more than three substitutions relative to the amino acid sequence of TQDWHRI (SEQ ID NO: 941) in loop VIII. In some embodiments, the AAV capsid variant comprises the amino acid sequence of TQDWHRI (SEQ ID NO: 941) in loop VIII.

[0139] In some embodiments, the AAV capsid variant comprises an amino acid sequence as described herein, e.g., an amino acid sequence of TTJ-001. e.g., as described in Tables 3 and 4A. In some embodiments, the AAV capsid variant is or comprises TTJ-001. In some embodiments, the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 941 in a loop VIII region.

[0140] In some embodiments, the AAV capsid variant comprises a VP1, VP2, and / or VP3 protein comprising an amino acid sequence described herein, e.g., an amino acid sequence of TTJ-001, e.g., as described in Tables 3 and 4A.

[0141] In some embodiments, the AAV capsid variant comprises an amino acid sequence encoded by a nucleotide sequence as described herein, e.g., a nucleotide sequence encoding TTJ-001, e.g., as described in Tables 3 and 4B.

[0142] In some embodiments, the polynucleotide or nucleic acid encoding the AAV capsid variant comprises a nucleotide sequence described herein, e.g., a nucleotide sequence encoding TTJ-001, e.g., as described in Tables 3 and 4B.Table 3. Exemplary full length capsid sequencesTable 4A. Exemplary full length capsid amino acid sequencesTable 4B. Exemplary full length capsid nucleic acid sequences

[0143] In some embodiments, the polynucleotide encoding an AAV capsid variant comprises the nucleotide sequence of SEQ ID NO: 983, or a nucleotide sequence with at least 70% (c.g., at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity thereto.

[0144] In some embodiments, the nucleotide sequence encoding an AAV capsid variant described herein, comprises a nucleotide sequence comprising at least one, at least two, or at least three modifications but not more than 30, not more than 20, or not more than 10 modifications, relative to the nucleotide sequence of SEQ ID NO: 983. In some embodiments, the nucleotide sequence encoding an AAV capsid variant described herein, comprises a nucleotide sequence comprising at least one, at least two, or at least three substitutions, but not more than 30, not more than 20, or not more than 10 substitutions relative to the amino acid sequence of SEQ ID NO: 983. In some embodiments, the nucleic acid sequence encoding an AAV capsid variant described herein is codon optimized.

[0145] In some embodiments, the AAV capsid variant comprises one or more substitutions in loop VIII and comprises the amino acid sequence of SEQ ID NO: 981, or an amino acid sequence with at least 70% (e.g.. at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99%) sequence identity thereto. In some embodiments, an AAV capsid variant described herein comprises an amino acid sequence comprising at least one, at least two. or at least three modifications, but not more than 30, not more than 20, or not more than 10 modifications, relative to the amino acid sequence of SEQ ID NO: 981. In some embodiments, an AAV capsid variant described herein comprises an amino acid sequence comprising at least one, at least two,or at least three substitutions, but not more than 30, not more than 20. or not more than 10 substitutions, relative to the amino acid sequence of SEQ ID NO: 981.

[0146] In some embodiments, the AAV capsid variant comprises one or more substitutions in loop VIII and comprises an amino acid sequence encoded by the nucleotide sequence of SEQ ID NO: 983, or a nucleotide sequence with at least 70% (e.g., at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity thereto. In some embodiments, an AAV capsid variant described herein comprises an amino acid sequence encoded by a nucleotide sequence comprising at least one, at least two, or at least three substitutions, but not more than 30. not more than 20, or not more than 10 substitutions, relative to the amino acid sequence of SEQ ID NO: 983. In some embodiments, an AAV capsid variant described herein comprises an amino acid sequence encoded by a nucleotide sequence comprising at least one, at least two, or at least three modifications, but not more than 30. not more than 20, or not more than 10 modifications, relative to the nucleotide sequence of SEQ ID NO: 983.

[0147] In some embodiments, an AAV capsid variant described herein comprises a VP1, VP2, VP3 protein, wherein at least one of the VP1. VP2, and VP3 comprise one or more substitutions in loop VIII. In some embodiments, the AAV capsid variant comprises amino acids 138-736, e g., a VP2, of the amino acid sequence of SEQ ID NO: 981, or an amino acid sequence with at least 70% (e g., at least 70%. at least 75%, at least 80%, at least 85%, at least 90%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity thereto. In some embodiments, the AAV capsid protein comprises amino acids 203-736, e.g., a VP3. of the amino acid sequence of SEQ ID NO: 981, or an amino acid sequence with at least 70% (e.g., at least 70%, at least 75%, at least 80%, at least 85%. at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity thereto. In some embodiments, the AAV capsid variant comprises amino acids 1-736, e.g., a VP1, of the amino acid sequence of SEQ ID NO: 981, or an amino acid sequence with at least 70% (e.g., at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%) sequence identity thereto.

[0148] In some embodiments, an AAV capsid variant described herein comprises the amino acid sequence of amino acids 203-736 of SEQ ID NO: 981. or an amino acid sequence at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical thereto. In some embodiments, an AAV capsid variant described herein comprises the amino acid sequence of amino acids 138-736 of SEQ ID NO: 981, or an amino acid sequence at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical thereto. In some embodiments, an AAV capsid variant described herein comprises the amino acid sequence of SEQ ID NO: 981, or an amino acid sequence at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto.

[0149] In some embodiments, an AAV capsid variant described herein has an increased tropism for a CNS cell or tissue, e.g., a brain cell, brain tissue, spinal cord cell, or spinal cord tissue, relative to the tropism of an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138.

[0150] In some embodiments, an AAV capsid variant described herein transduces a brain region, e.g., a midbrain region (e.g., the hippocampus, or thalamus) or the brain stem. In some embodiments, the level of transduction is at least 39, at least 50, at least 100, at least 120, at least 132, at least 146, at least 150, at least 161, at least 174, at least 175, at least 200, at least 225, at least 250, at least 275, at least 283, at least 300, at least 350, at least 400, at least 450, at least 500, at least 525, at least 528, or at least 550- fold greater as compared to an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138.

[0151] In some embodiments, an AAV capsid variant described herein is enriched at least 10, at least 14, at least 20. at least 24, at least 50, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 425, at least 450, or at least 460-fold in die brain compared to enrichment in the brain of an AAV capsid comprising the ammo acid sequence of SEQ ID NO: 138. In some embodiments, an AAV capsid variant described herein is enriched at least 200, at least 250, at least 300, at least 350. at least 400. at least 425. at least 450. or at least 460-fold in the brain compared to enrichment in the brain of an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138.

[0152] In some embodiments, an AAV capsid variant described herein is enriched in the brain of at least two to three species, e.g., a non-human primate and rodent (e.g., mouse) species, compared to enrichment in the brain of an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138. In some embodiments, an AAV capsid variant described herein is enriched at least 2. at least 3, at least 5, at least 10. at least 15, at least 20, at least 25. at least 30, at least 35, at least 40, at least 45, at least 50. at least 55. at least 60, at least 65, at least 70. at least 75, at least 80, at least 85, at least 90, at least 95. at least 100, at least 105, at least 115, at least 120, at least 125, at least 130, at least 135, at least 140, at least 145, at least 150. at least 155. at least 160. at least 165. at least 170. at least 175. at least 180, at least 190, at least 200, at least 205, or at least 210-fold in the brain of at least two to three species, e.g., a non- human primate and rodent (e.g., mouse) species, compared to enrichment in the brain of an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138. In some embodiments, the at least tw o to three species arc Macaca fascicularis, Chlorocebus sabaeus, Callithrix jacchus, and / or mouse (e.g., outbred mice).

[0153] In some embodiments, an AAV capsid variant described herein is enriched at least 2, at least 3. at least 4, at least 5, at least 10. at least 15, at least 17, at least 20, at least 50, at least 75, at least 100, at least 103, at least 107, at least 125, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 450, at least 500, at least 750, at least 1000, or at least 1200-fold in the brain compared to enrichment in the brain of an AAV capsid comprising the amino acid sequence of SEQ ID NO: 981.

[0154] In some embodiments, an AAV capsid variant described herein delivers an increased level of viral genomes to a brain region. In some embodiments, the level of viral genomes is increased by at least 2. at least 5. at least 7, at least 10. at least 15, at least 19. at least 20, at least 22, or at least 25-fold, as compared to the level of viral genomes delivered by an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138. In some embodiments, the brain region comprises a sensory cortex, motor cortex, putamen, thalamus, caudate, hippocampus, and / or cerebellum.

[0155] In some embodiments, an AAV capsid variant delivers an increased level of a payload to a brain region. In some embodiments, the level of the payload is increased by at least 39, at least 50, at least 100, at least 120, at least 132, at least 146, at least 150, at least 161, at least 174, at least 175, at least 200, at least 225, at least 250, at least 275, at least 283, at least 300, at least 350, at least 400, at least 450, at least 500, at least 525, at least 528, or at least 550-fold, as compared to the level of a pay load delivered by an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138. In some embodiments, the brain region comprises a sensory cortex, motor cortex, putamen, thalamus, caudate, hippocampus, and / or cerebellum.

[0156] In some embodiments, an AAV capsid variant described herein is enriched at least 5, at least 10, at least 50. at least 100. at least 115. at least 120. at least 150. at least 175. at least 200. at least 207. at least 225, at least 250, or at least 275-fold in tire spinal cord compared to enrichment in the spinal cord of an AAV capsid comprising the amino acid sequence of SEQ ID NO: 138.

[0157] In some embodiments, an AAV capsid variant of the present disclosure has decreased tropism for the liver. In some embodiments, an AAV capsid variant comprises a modification that results in reduced tropism (e.g., de-targeting) and / or activity in the liver. In some embodiments, the reduced tropism in the liver is compared to an otherwise similar capsid that does not comprise the modification, e.g.. a wild-type capsid polypeptide. In some embodiments, an AAV capsid variant comprises a modification that results in one or more of the following properties: (1) reduced tropism in the liver; (2) de-targeted expression in the liver; (3) reduced activity in the liver; and / or (4) reduced binding to galactose. In some embodiments, the reduction in any one or all of properties ( l)-(3) is compared to an otherwise similar AAV capsid variant that does not comprise the modification. Exemplary modifications are provided in WO 2018 / 119330; Pulicherla et al. (2011) Mol. Ther. 19(6): 1070-1078; Adachi et al. (2014) Nature Communications 5(3075), DOI: 10.1038 / ncomms4075; and Bell et al. (2012) J. Virol. 86(13): 7326-33; the contents of which are hereby incorporated by reference in their entirety .

[0158] In some embodiments, the AAV capsid variant comprises a modification at an amino acid corresponding to N470 (e.g., comprises N470A at an amino acid corresponding to N470) of the amino acid sequence of SEQ ID NO: 138; an amino acid corresponding to D271 (e.g., comprises D271 A at an amino acid corresponding to D271) of the amino acid sequence of SEQ ID NO: 138; an amino acid corresponding to N272 (e.g., comprises N272A at an amino acid corresponding to N272) of the amino acid sequence of SEQ ID NO: 138; an amino acid corresponding to Y446 (e.g., comprises Y446A at an amino acid corresponding to Y446) of the amino acid sequence of SEQ ID NO: 138; an amino acid corresponding to N498 (e.g., comprises N498Y or N498I at an amino acid corresponding to N498) of the amino acid sequence of SEQ ID NO: 138; an amino acid corresponding to W503 (e.g., comprises W503R or W503A at an amino acid corresponding to W503) of the amino acid sequence of SEQ ID NO: 138; an amino acid corresponding to L620 (e.g.. comprises L620F at an amino acid corresponding to L620) of the amino acid sequence of SEQ ID NO: 138; or a combination thereof. In some embodiments, the AAV capsid variant comprises one. two, three, four, five, or all of an amino acid other than N at aposition corresponding to position 470 (e.g., comprises A at an amino acid corresponding to position 470) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than D at a position corresponding to position 271 (e.g., comprises A at an amino acid corresponding to position 271) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than N at a position corresponding to position 272 (e.g., comprises A at an amino acid corresponding to position 272) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than Y at a position corresponding to position 446 (e.g., comprises A at an amino acid corresponding to position 446) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than N at a position corresponding to position 498 (e.g., comprises Y or I at an amino acid corresponding to position 498) of the amino acid sequence of SEQ ID NO: 138; an amino acid other than W at a position corresponding to position 503 (e.g., comprises R or A at an amino acid corresponding to position 503) of the amino acid sequence of SEQ ID NO: 138; and an amino acid other than L at a position corresponding to position 620 (e.g., comprises F at an amino acid corresponding to position 620) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant comprises a modification at positions corresponding to amino acid N470 (e.g., comprises N470A at an amino acid corresponding to N470) of the amino acid sequence of SEQ ID NO: 138; corresponding to amino acid D271 (e.g., comprises D271 A at an amino acid corresponding to D271) of the amino acid sequence of SEQ ID NO: 138; corresponding to amino acid N272 (e.g., comprises N272A at an amino acid corresponding to N272) of the amino acid sequence of SEQ ID NO: 138; corresponding to amino acid Y446 (e.g.. comprises Y446A at an amino acid corresponding to Y446) of the amino acid sequence of SEQ ID NO: 138; and corresponding to amino acid W503 (e.g., comprises W503R or W503A at an amino acid corresponding to W503) of the amino acid sequence of SEQ ID NO: 138. In some embodiments, the AAV capsid variant comprises a modification corresponding to amino acid N498 (e.g., comprises N498Y at an amino acid corresponding to N498) of the amino acid sequence of SEQ ID NO: 138 and corresponding to amino acid L620 (e.g., comprises L620F at an amino acid corresponding to L620) of the amino acid sequence of SEQ ID NO: 138.

[0159] In some embodiments, the AAV capsid variant comprises a modification as described in Adachi et al. (2014) Nature Communications 5(3075), DOI: 10.1038 / ncomms4075, the contents of which are hereby incorporated by reference in their entirety. Exemplaty modifications that alter or do not alter tissue transduction in at least the brain, liver, heart, lung, and / or kidney can be found in Supplementary Data 2 showing the AAV Barcode-Seq data obtained with AAV9-AA-VBCLib of Adachi et al. (supra), the contents of which are hereby incorporated by reference in their entirety.

[0160] In some embodiments, the AAV capsid variant is an isolated capsid variant. In some embodiments, the AAV capsid variant is a recombinant capsid variant. In some embodiments, a polynucleotide encoding an AAV capsid polypeptide, e.g.. an AAV capsid variant is an isolated and / or a recombinant AAV capsid polypeptide.

[0161] Also provided herein are polynucleotide sequences encoding any of the AAV capsid variants described above and AAV particles, vectors, and cells comprising the same.Exemplary Properties of AAV Capsids

[0162] In some embodiments, the AAV particle may comprise a capsid protein or variant of any natural or recombinant AAV serotype. AAV serotypes may differ in characteristics such as, but not limited to. packaging, tropism, transduction and immunogenic profdes. Without being bound by theory, it is believed in some embodiments that the AAV capsid protein, e.g., an AAV capsid variant, can modulate AAV particle tropism in a particular tissue.10163] In some embodiments, the AAV capsid variant allows for blood brain barrier penetration following intravenous administration. In some embodiments, the AAV capsid variant allows for blood brain barrier penetration following intravenous administration, focused ultrasound (FUS), e.g., coupled with the intravenous administration of microbubbles (FUS-MB), or MRI-guided FUS coupled with intravenous administration. In some embodiments, the AAV capsid variant allows for increased distribution to a CNS region, e.g.. a brain region. In some embodiments, the CNS region comprises the amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, and / or temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus. gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region). In some embodiments, the AAV capsid variant allows for preferential transduction in a brain region relative to the transduction in the dorsal root ganglia (DRG). In some embodiments, the AAV capsid variant allows for preferential transduction in a brain region relative to the transduction in the liver. In some embodiments, the AAV capsid variant allows for transduction in neuronal cells. In some embodiments, the AAV capsid variant allows for transduction in a non-neuronal cell, e.g., a glial cell (e.g., an astrocyte, an oligodendrocyte, or a combination thereof). In some embodiments, the AAV capsid variant allows for transduction in both neuronal cells and non-neuronal cell, e.g., a glial cell (e.g., an astrocyte, an oligodendrocyte, or a combination thereof).

[0164] In some embodiments, an AAV capsid variant allows for increased distribution to a spinal cord region. In some embodiments, the spinal region comprises a cervical spinal cord region, thoracic spinal cord region, and / or lumbar spinal cord region.

[0165] In some embodiments, the AAV capsid variant allows for increased distribution to a heart region.

[0166] In some embodiments, the AAV capsid variant is suitable for intramuscular administration and / or transduction of muscle fibers. In some embodiments, the AAV capsid variant allows for increased distribution to a muscle region. In some embodiments, the muscle region comprises a heart muscle, quadriceps muscle, skeletal muscle, a diaphragm muscle region, or a combination thereof. In some embodiments, the muscle region comprises a heart muscle region, e.g., a heart atrium muscle region or a heart ventricle muscle region.

[0167] In some embodiments, the AAV capsid variant is suitable for increased distribution to a kidney. In some embodiments, the AAV capsid variant is suitable for increased distribution to a pancreas.

[0168] In some embodiments, the initiation codon for translation of the AAV VP1 capsid protein, e.g., a capsid variant, described herein may be CTG, TTG, or GTG as described in US Patent No. US8163543, the contents of which are herein incorporated by reference in its entirety.

[0169] The present disclosure refers to structural capsid proteins (including VP1, VP2 and VP3) which are encoded by capsid (Cap) genes. These capsid proteins form an outer protein structural shell (e.g., capsid) of a viral vector such as AAV. VP capsid proteins synthesized from Cap polynucleotides generally include a methionine as the first amino acid in the peptide sequence (Metl), which is associated with the start codon (AUG or ATG) in the corresponding Cap nucleotide sequence. However, it is common for a first-methionine (Metl) residue or generally any first amino acid (AA1) to be cleaved off after or during polypeptide synthesis by protein processing enzymes such as Met-aminopeptidases. This “Met / AA-clipping” process often correlates with a corresponding acetylation of the second amino acid in the polypeptide sequence (e.g., alanine, valine, serine, threonine, etc.). Met-clipping commonly occurs with VP1 and VP3 capsid proteins but can also occur with VP2 capsid proteins.

[0170] Where the Met / AA-clipping is incomplete, a mixture of one or more (one, two or three) VP capsid proteins comprising the viral capsid may be produced, some of which may include a Metl / AAl amino acid (Met+ / AA+) and some of which may lack a Metl / AAl amino acid as a result of Met / AA- clipping (Met- / AA-). For further discussion regarding Met / AA-clipping in capsid proteins, see Jin, et al. Direct Liquid Chromatography / Mass Spectrometry Analysis for Complete Characterization of Recombinant Adeno- Associated Virus Capsid Proteins. Hum Gene Ther Methods. 2017 Oct. 28(5):255- 267; Hwang, et al. N-Terminal Acetylation of Cellular Proteins Creates Specific Degradation Signals. Science. 2010 February 19. 327(5968): 973-977; the contents of which are each incorporated herein by reference in its entirety .

[0171] According to the present disclosure, references to capsid proteins, e.g., AAV capsid variants, is not limited to either clipped (Met- / AA-) or unclipped (Met+ / AA+) and may, in context, refer to independent capsid proteins, viral capsids comprised of a mixture of capsid proteins, and / or polynucleotide sequences (or fragments thereof) which encode, describe, produce or result in capsid proteins of the present disclosure. A direct reference to a capsid protein or capsid polypeptide (such as VP1, VP2 or VP2) may also comprise VP capsid proteins which include a Metl / AAl amino acid (Met+ / AA+) as well as corresponding VP capsid proteins which lack the Metl / AAl amino acid as a result of Met / AA-clipping (Met- / AA-).

[0172] Further according to the present disclosure, a reference to a specific SEQ ID NO (whether a protein or nucleic acid) which comprises or encodes, respectively, one or more capsid proteins which include a Metl / AAl amino acid (Met+ / AA+) should be understood to teach the VP capsid proteins which lack the Metl / AAl amino acid as upon review of the sequence, it is readily apparent any sequence which merely lacks the first listed amino acid (whether or not Metl / AAl).

[0173] As a non-limiting example, reference to a VP 1 polypeptide sequence which is 736 amino acids in length and which includes a “Metl" amino acid (Met+) encoded by the AUG / ATG start codon may also be understood to teach a VP1 polypeptide sequence which is 735 amino acids in length and which does not include the “Metl” amino acid (Met-) of the 736 amino acid Met+ sequence. As a second non-limiting example, reference to a VP 1 polypeptide sequence which is 736 ammo acids in length and which includes an “AA1” amino acid (AA1+) encoded by any NNN initiator codon may also be understood to teach a VP1 polypeptide sequence which is 735 amino acids in length and which does not include the “AA1” amino acid (AA1-) of the 736 amino acid AA1+ sequence.

[0174] References to viral capsids formed from VP capsid proteins (such as reference to specific AAV capsid serotypes), can incorporate VP capsid proteins which include a Metl / AAl amino acid (Met+ / AA1+), corresponding VP capsid proteins which lack the Metl / AAl amino acid as a result of Met / AAl -clipping (Met- / AA1-), and combinations thereof (Met+ / AA1+ and Met- / AA1-).

[0175] As a non-limiting example, an AAV capsid serotype can include VP1 (Met+ / AA1+). VP1 (Met- / AA1-), or a combination of VP1 (Met+ / AA1+) and VP1 (Met- / AA1-). An AAV capsid serotype can also include VP3 (Met+ / AA1+). VP3 (Met- / AA1-), or a combination of VP3 (Met+ / AA1+) and VP3 (Met- / AA1-); and can also include similar optional combinations of VP2 (Met+ / AA1) and VP2 (Met- / AA1-).Additional AAV Capsid Sequences

[0176] In some embodiments, the AAV capsid variant comprises at amino acids corresponding to positions 582, 583, 584, 585, 586, 587, 588, 589, and / or 590 of the amino acid sequence of SEQ ID NO: 138, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14, or at least 15 consecutive amino acids of any one of the amino acid sequences provided in Table 1, 2A, 2B, 9, 24, 25, or 26.

[0177] hi some embodiments, the AAV capsid variant comprises, immediately subsequent to an amino acid corresponding to position 582, 583, 584, 585, 586, 587, 588, 589, and / or 590 of the amino acid sequence of SEQ ID NO: 138 (e.g., corresponding to equivalent positions in any other AAV serotype (e.g., AAV1, AAV2, AAV3, AAV3b, AAV4, AAV6. AAV7, AAV8, AAV9, AAVrh8, AAVrhlO, AAVrh32.33. AAVrh74, PHP.N, PHP.B. or an AAV serotype as provided in Table 6 of WO 2021 / 230987 (the contents of which are hereby incorporated by reference in their entirety))), at least 3, at least 4, at least 5, at least 6, at least 7. at least 8, at least 9, at least 10. at least 11, at least 12, at least 13. at least 14, or at least 15 consecutive amino acids of any one of the amino acid sequences provided in Table 1. 2A, 2B. 9, 24. 25. or 26. In some embodiments, the at least 3, at least 4, at least 5. at least 6. at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14, or at least 15 consecutive amino acids of any one of the amino acid sequences provided in Table 1, 2A, 2B, 9, 24, 25. or 26 replaces at least one, at least two. at least three, at least four, at least five, at least six. at least seven, at least eight, or all of amino acid(s) corresponding to position(s) 582. 583, 584, 585. 586, 587, 588. 589, and / or 590 (e.g., T582, N583. H584, Q585, S586, A587, Q588. A589, and / or Q590) of the amino acidsequence of SEQ ID NO: 138 (e.g., corresponding to equivalent positions in any other AAV serotype (e.g., AAV1, AAV2, AAV3, AAV3b, AAV4, AAV6, AAV7, AAV8, AAV9, AAVrh8, AAVrhlO, AAVrh32.33, AAVrh74, PHP.N, PHP.B, or an AAV serotype as provided in Table 6 of WO 2021 / 230987, which is hereby incorporated by reference in its entirety)). In some embodiments, the AAV capsid variant comprises an amino acid other than the wild-type amino acid, at one, two. three, four, five, six, seven, eight, or all of amino acid(s) corresponding to position(s) 582, 583, 584, 585. 586, 587, 588, 589, and / or 590 of the amino acid sequence of SEQ ID NO: 138 (e.g., corresponding to equivalent positions in any other AAV serotype (e.g., AAV1. AAV2, AAV3, AAV3b, AAV4, AAV6, AAV7. AAV8, AAV9, AAVrh8, AAVrhlO, AAVrh32.33, AAVrh74, PHP.N, PHP.B, or an AAV serotype as provided in Table 6 of WO 2021 / 230987. which is hereby incorporated by reference in its entirety). In some embodiments, the AAV capsid variant comprises a modification replacing one, two, three, four, five, six, seven, eight, or all amino acid(s) corresponding to position / s) 582. 583, 584. 585, 586, 587. 588, 589, and / or 590 (e.g., T582, N583, H584. Q585, S586, A587, Q588, A589. and / or Q590) of the amino acid sequence of SEQ ID NO: 138 (e.g., corresponding to equivalent positions in any other AAV serotype (e.g., AAV1, AAV2. AAV3, AAV3b. AAV4. AAV6, AAV7, AAV8. AAV9. AAVrh8, AAVrhlO. AAVrh32.33, AAVrh74. PHP.N. PHP.B, or an AAV serotype as provided in Table 6 of WO 2021 / 230987, which is hereby incorporated by reference in its entirety).

[0178] In some embodiments, the AAV capsid variant may comprise a variant of a VOY101 capsid polypeptide, an AAVPHP.B (PHP.B) capsid polypeptide, an AAVPHP.N (PHP.N) capsid polypeptide, an AAV1 capsid polypeptide, an AAV2 capsid polypeptide, an AAV5 capsid polypeptide, an AAV9 capsid polypeptide, an AAV9 K449R capsid polypeptide, or an AAVrhlO capsid polypeptide. In some embodiments, the AAV capsid polypeptide, e.g., AAV capsid variant, comprises an amino acid sequence of any one of the AAV capsid polypeptides in Table 5, or an amino acid sequence substantially identical (e.g., having at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, or at least 99% sequence identity ) thereto. In some embodiments, the nucleotide sequence encoding the AAV capsid polypeptide comprises any one of the nucleotide sequences in Table 5, or a nucleotide sequence substantially identical (e.g., having at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, or at least 99% sequence identity) thereto.Table 5. AAV SequencesAAV Viral Genome

[0179] In some embodiments, the AAV particle of the present disclosure serves as an expression vector comprising a viral genome that encodes a FXN protein (e.g., a wildtvpc FXN protein, e.g., a wildtype human FXN protein).

[0180] In some embodiments, an AAV particle, e.g.. an AAV particle for the vectorized delivery of a FXN protein described herein, comprises a viral genome, e.g., an AAV viral genome, also referred to as an AAV genome, a vector genome, or an AAV vector genome. In some embodiments, the viral genome, e.g., tire AAV viral genome, further comprises an inverted terminal repeat (ITR) region, an enhancer, a promoter, an intron region, an exon region, a nucleic acid encoding a transgene encoding a FXN protein sequence, e.g., any one of the sequences in Table 6G or a sequence that is at least 90% identical to any one of the sequences provided in Table 6G). a nucleotide sequence encoding at least one miR binding site (e.g., at least one miR122 binding site), a polyA region, or a combination thereof.Viral Genome Component: Inverted Terminal Repeats (ITRs)

[0181] In some embodiments, the viral genome may comprise at least one inverted terminal repeat (ITR) region. The AAV particles of the present disclosure comprise a viral genome with at least one ITR region and a FXN-encoding sequence. In some embodiments, the viral genome has two ITRs. These two ITRs flank the FXN-encoding sequence at the 5’ and 3’ ends. In some embodiments, the ITR functions as an origin of replication comprising a recognition site for replication. In some embodiments, the ITR comprises a sequence region which can be complementary and symmetrically arranged. In some embodiments, the ITR incorporated into a viral genome described herein may be comprised of a naturally occurring polynucleotide sequence or a recombinantly derived polynucleotide sequence.

[0182] In some embodiments, the AAV viral genome may comprise at least one inverted terminal repeat (ITR) region having a length of 50-250 nucleotides. In some embodiments, the AAV viral genome comprises a 5' ITR region that is 50-250 nucleotides in length and a 3’ ITR region that is 50-250 nucleotides in length. In some embodiments, tire 5’ ITR region and the 3‘ ITR region may comprise the same length and / or the same sequence. In some embodiments, the 5’ ITR region and the 3’ ITR region are different in length and / or in sequence.

[0183] Non-limiting examples of ITR sequence regions are described in Table 6A. In some embodiments, the viral genome comprises an ITR comprising the nucleotide sequence of SEQ ID NO: 1811 or a sequence that is at least 80% identical (e.g., at least 80%. at least 85%, at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto. In some embodiments, the viral genome comprises an ITR comprising the nucleotide sequence of SEQ ID NO: 1812 or a sequence that is at least 80% identical (e.g., at least 80%, at least 85%. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto. In some embodiments, the viral genome comprises a 5' ITR region comprising the nucleotide sequence of SEQ ID NO: 1811 or a sequence that is at least 80% identical (e.g., at least 80%. at least 85%, at least 90%, at least 91%. at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or the viral genome comprises a 3' ITR region comprising the nucleotide sequence of SEQ ID NO: 1812 or a sequence that is at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.Table 6A. Exemplary Inverted Terminal Repeat (ITR) Sequence RegionsViral Genome Component: Promoters and Enhancers

[0184] In some embodiments, the viral genome comprises at least one element to enhance the transgene target specificity and expression. See, e.g., Powell et al. Viral Expression Cassette Elements to Enhance Transgene Target Specificity and Expression in Gene Therapy, 2015; the contents of which are herein incorporated by reference in their entirety. Non-limiting examples of elements to enhance the transgene target specificity and expression include promoters, endogenous miRNAs, post-transcriptional regulatory elements (PREs), polyadenylation (Poly A) region, upstream enhancers (USEs). CMV enhancers, and introns.

[0185] In some embodiments, expression of the polypeptides in a target cell may be driven by a specific promoter, including but not limited to. a promoter that is species specific, inducible, tissuespecific. or cell cycle-specific (Parr et al., Nat. Med.3 l 145-9 (1997); the contents of which are herein incorporated by reference in their entirety).

[0186] In some embodiments, the viral genome comprises a promoter that is sufficient for expression, e g., in a target cell, of a FXN protein, e.g.. a human FXN protein, encoded by a transgene. In some embodiments, the promoter is deemed to be efficient when it drives expression of the FXN encoded in viral genome of the AAV particle.

[0187] In some embodiments, the promoter is deemed to be efficient when it drives expression in the cell or tissue being targeted.

[0188] Promoters may be naturally occurring or non-naturally occurring. Non-limiting examples of promoters include viral promoters, plant promoters and mammalian promoters. In some embodiments, the promoter may be a human promoter. In some embodiments, the promoter may be truncated.

[0189] Promoters that promote expression in most tissues include, but are not limited to, human elongation factor la-subunit (EFla) promoters, immediate-early cytomegalovirus (CMV) promoters, chicken (3-actin (CBA) promoters, CAG promoters, CAG derivative promoters, (3 glucuronidase (GUSB) promoters, ubiquitin C (UBC) promoters, or a fragment of any one of the aforementioned. A CAG promoter typically comprises: (C) the cytomegalovirus early enhancer element; (A) the promoter, the first exon, and the first intron of the chicken beta-actin gene, and (G) the splice acceptor of the rabbit beta-globin gene. In some embodiments, a derivative of a CAG promoter may comprise (i) a CMVie enhancer and a beta-actin promoter or (ii) a beta-actin promoter and an intron sequence.

[0190] Tissue-specific expression elements can be used to restrict expression to certain cell types such as. but not limited to, nervous system promoters which can be used to restrict expression to neurons, astrocytes, or oligodendrocytes. Non-limiting examples of tissue-specific expression elements for neurons include neuron-specific enolase (NSE). platelet-derived growth factor (PDGF), platelet-derived growth factor B-chain (PDGF- ). synapsin (Syn). methyl-CpG binding protein 2 (MeCP2), CaMKII. mGluR2, NFL, NFH, n(32, PPE, Enk, and EAAT2 promoters. Non-limiting examples of tissue-specific expression elements for astrocytes include the glial fibrillary acidic protein (GFAP) and EAAT2 promoters. A non-limiting example of a tissue-specific expression element for oligodendrocytes include the myelin basic protein (MBP) promoter.

[0191] In some embodiments, the viral genome comprises a ubiquitous promoter. Non-limiting examples of ubiquitous promoters include Hl, U6. CMV, CBA (including derivatives CAG, CBh, etc.), EF-la, PGK, UBC, GUSB (hGBp), and UCOE (promoter of HNRPA2B1-CBX3).

[0192] In some embodiments, the viral genome comprises a CBA promoter. In some embodiments, the viral genome comprises a truncated CBA promoter, e.g., a CBA promoter that is 50-400 nucleotides in length, e.g., 100-332 nucleotides in length. In some embodiments, the viral genome comprises a CMV promoter. In some embodiments, the viral genome comprises a truncated CMV promoter, e.g., a CMV promoter that is 50-300 nucleotides in length, e.g., a CMV promoter that is 109 nucleotides in length.

[0193] In some embodiments, the AAV vector comprises an enhancer element, a promoter, and / or a 5’UTR intron. The enhancer may be, but is not limited to, a CMV enhancer; the promoter may be, but is not limited to, a CMV, CBA, FXN, UBC, GUSB, NSE, Synapsin, MeCP2, or GFAP promoter; and the 5’UTR / intron may be, but is not limited to, SV40, and CBA-MVM. In some embodiments, the enhancer, promoter, and / or intron used in combination may be: (1) CMV enhancer, CMV promoter, SV40 5‘UTR intron; (2) CMV enhancer, CBA promoter, SV40 5’UTR intron; (3) CMV enhancer, CBA promoter, CBA-MVM 5’UTR intron: (4) UBC promoter; (5) GUSB promoter; (6) NSE promoter; (7) Synapsin promoter; (8) MeCP2 promoter; (9) GFAP promoter; (10) Hl promoter; and / or (11) U6 promoter.

[0194] In some embodiments, the viral genome comprises an engineered promoter.

[0195] In some embodiments, the viral genome comprises an enhancer. In some embodiments, an enhancer may be a separate component of the viral genome than the promoter. In some embodiments, anenhancer may be 5’ to a promoter sequence in a viral genome. In some embodiments, an enhancer may be 3’ to a promoter sequence in a viral genome.

[0196] In some embodiments, the viral genome comprises an enhancer, for example an immediate- early “ie” enhancer or a CMV / globin enhancer. In some embodiments, the enhancer comprises iel exon 1 and iel intron 1 or a fragment thereof. In some embodiments, the enhancer comprises an iel exon 1, an iel intron 1 or fragment thereof, a human beta-globin intron 2, and a human beta-globin exon 3.

[0197] In some embodiments, an enhancer may comprise at least one intron sequence. In some embodiments, an enhancer may comprise at least one exon sequence. In some embodiments, an enhancer comprises one intron sequence and one exon sequence. In some embodiments, an enhancer sequence comprises two intron sequences. In some embodiments, an enhancer sequence comprises two exon sequences. In some embodiments, an enhancer sequence comprises two intron sequences and two exon sequences.

[0198] Exemplary promoters are provided in Table 6B. In some embodiments, the promoter comprises or consists of any one of the nucleotide sequences provided in Table 6B, or a nucleotide sequence at least 90% (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) identical thereto. In some embodiments, the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1738. In some embodiments, the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1740. In some embodiments, the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1742. In some embodiments, the promoter comprises or consists of the nucleotide sequence of SEQ ID NO: 1745.

[0199] In some embodiments, the promoter comprises a nucleotide sequence at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% to the nucleotide sequence of SEQ ID NO: 1742. In some embodiments, the promoter comprises a nucleotide sequence at least 95% identical to SEQ ID NO: 1742. In some embodiments, the promoter comprises a nucleotide sequence at least 98% identical to SEQ ID NO: 1742. In some embodiments, the promoter comprises a nucleotide sequence at least 99% identical to SEQ ID NO: 1742. In some embodiments, the promoter comprises the nucleotide sequence of SEQ ID NO: 1742.Table 6B. Exemplary PromotersViral Genome Component: Introns and Exon Sequences

[0200] In some embodiments, the AAV viral genome comprises at least one intron and / or exon sequence region.

[0201] In some embodiments, the AAV viral genome may comprise at least one intron sequence region. The intron sequence region(s) may be 10-1200 nucleotides in length. As a non-limiting example, the viral genome comprises an intron sequence region that is about 32 nucleotides in length. As a nonlimiting example, the viral genome comprises an intron sequence region that is about 53 nucleotides in length. As a non-limiting example, the viral genome comprises an intron sequence region that is about 134 nucleotides in length. As a non-limiting example, the viral genome comprises an intron sequence region that is about 347 nucleotides in length. As a non-limiting example, the viral genome comprises an intron sequence region that is about 379 nucleotides in length. As a non-limiting example, the viral genome comprises an intron sequence region that is about 566 nucleotides in length. As a non-limiting example, the viral genome comprises an intron sequence region that is about 1016 nucleotides in length. As a non-limiting example, the viral genome comprises an intron sequence region that is more than 1016 nucleotides in length.

[0202] In some embodiments, the AAV viral genome comprises two intron sequence regions. In some embodiments, the AAV viral genome comprises three intron sequence regions. In some embodiments, the AAV viral genome comprises more than three intron sequence regions.

[0203] In some embodiments, the AAV viral genome may comprise at least one exon sequence region. In some embodiments, the exon sequence may be 10-1200 nucleotides in length. As a nonlimiting example, the viral genome comprises an exon region that is about 32 nucleotides in length. As a non-limiting example, the viral genome comprises an exon sequence region that is about 53 nucleotides in length. As a non-limiting example, the viral genome comprises an exon sequence region that is about 134 nucleotides in length. As a non-limiting example, the viral genome comprises an exon sequence region that is about 347 nucleotides in length. As a non-limiting example, the viral genome comprises an exon sequence region that is about 379 nucleotides in length. As a non-limiting example, the viral genome comprises an exon sequence region that is about 566 nucleotides in length. As a non-limiting example, the viral genome comprises an exon sequence region that is about 1016 nucleotides in length. As a non-limiting example, the viral genome comprises an exon sequence region that is more than 1016 nucleotides in length.

[0204] In some embodiments, the AAV particle viral genome comprises two exon sequence regions. In some embodiments, the AAV particle viral genome comprises three exon sequence regions. In some embodiments, the AAV particle viral genome comprises more than three exon sequence regions.

[0205] In some embodiments, the AAV particle viral genome comprises a hybrid intron / exon sequence region comprising at least one intron and at least one exon. In some embodiments, the hybrid intron / exon sequence region comprises one intron and one exon. In some embodiments, the hybrid intron / exon sequence region comprises two introns and two exons. In some embodiments, an intron or exon sequence may comprise a full-length intron or exon. In some embodiments, an intron or exon sequence may comprise a fragment or variant of an intron or exon sequence.

[0206] The hybrid intron / exon sequence region(s) may, independently, have a length such as, but not limited to. 15-100. 100-200, 200-300. 300-400, 400-500, 500-600, 600-700, 700-800, 800-900, 900- 1000. 1000-1100, 1100-1200, and more than 1200 nucleotides. As a non-limiting example, the viral genome comprises a hybrid intron / exon sequence region that is about 379 nucleotides in length. As a non-limiting example, the viral genome comprises a hybrid intron / exon sequence region that is about 566 nucleotides in length. As a non-limiting example, the viral genome comprises a hybrid intron / exon region that is about 379 nucleotides in length.

[0207] In some embodiments, the intron / exon sequence region is an enhancer sequence. In some embodiments, the intron / exon sequence region is not an enhancer sequence.

[0208] In some embodiments, the intron / exon sequence region is a component of a promoter sequence. In some embodiments, the intron / exon sequence region is not a component of a promoter sequence.

[0209] In some embodiments, the AAV particle viral genome comprises at least one intron and / or exon sequence region. Non-limiting examples of intron and exon sequence regions are described in Table 6C. In some embodiments, the intron and / or exon sequence region comprises the nucleotide sequence of SEQ ID NO: 1816, or a nucleotide sequence w ith at least 70%, at least 75%, at least 80%, at least 85%, at least 90%. at least 95%, or at least 99% sequence identity thereto. In some embodiments, the exon sequence region comprises the nucleotide sequence of SEQ ID NO: 1817, or a nucleotide sequence with at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% sequence identity thereto. In some embodiments, the intron sequence region comprises the nucleotide sequence of SEQ ID NO: 1819, or a nucleotide sequence with at least at least 70%, at least 75%, at least 80%, at least 85%, at least 90%. at least 95%, or at least 99% sequence identity' thereto. In some embodiments, the intron sequence region comprises the nucleotide sequence of SEQ ID NO: 1820, or a nucleotide sequence with at least 70%, at least 75%. at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% sequence identity thereto. In some embodiments, the exon sequence region comprises the nucleotide sequence of SEQ ID NO: 1821, or a nucleotide sequence with at least 70%. at least 75%, at least 80%, at least 85%, at least 90%, at least 95%. or at least 99% sequence identity thereto.Table 6C. Exemplary Intron and Exon Sequence RegionsViral Genome Component: Nucleotide Sequence Encoding a miR Binding Site

[0210] Tissue- or cell-specific expression of the AAV viral particles of the disclosure can be enhanced by introducing tissue- or cell-specific regulatory’ sequences, e.g., promoters, enhancers. microRNA binding sites, e.g., a detargeting site. Without being bound by theory’, it is believed that an encoded miR binding site can modulate, e.g., prevent, suppress, or otherwise inhibit, the expression of a gene of interest on the viral genome of the invention, based on the expression of the corresponding endogenous microRNA (miRNA) or a corresponding controlled exogenous miRNA in a tissue or cell, e.g., a non-targeting cell or tissue. In some embodiments, a miR binding site modulates, e.g., reduces, expression of the FXN-encoding region in a viral genome of an AAV particle described herein in a cell or tissue where the corresponding mRNA is expressed. In some embodiments, the miR binding site modulates, e.g., reduces, expression of the encoded FXN protein in a cell or tissue of the DRG or liver.

[0211] In some embodiments, the viral genome of an AAV particle described herein comprises a nucleotide sequence encoding a microRNA binding site, e.g., a detargeting site. In some embodiments, the viral genome of an AAV particle described herein comprises a nucleotide sequence encoding a miR binding site, a microRNA binding site series (miR BSs). or a reverse complement thereof. In some embodiments, the 3' UTR of the viral genome may be engineered to include at least one miRNA binding site.

[0212] In some embodiments, the encoded miR binding site series comprise at least 1-5 copies, e.g., at least 1-3, 2-4, 3-5, or at least 1, at least 2, at least 3, at least 4, at least 5 copies or more of a miR binding site (miR BS). In some embodiments, the encoded miR binding site series comprises 3 copies of a miR binding site. In some embodiments, all copies are identical, e.g., comprise the same miR binding site. In some embodiments, the miR binding sites within the encoded miR binding site series are continuous and not separated by a spacer. In some embodiments, the miR binding sites within an encoded miR binding site series are separated by a spacer, e.g., a non-coding sequence.

[0213] In some embodiments, the viral genome comprises at least one nucleotide sequence encoding a miRNA binding site to reduce the expression of the transgene in a specific tissue. In some embodiments, the viral genome may comprise a nucleotide sequence encoding a miR122 binding site (miR122BS) or tandem copies of the miR122BS to reduce the expression of the viral genome in the liver. In some embodiments, the viral genome may comprise a nucleotide sequence encoding a miR183 miRNA binding site (miR183BS) or tandem copies of the miR183BS to reduce expression of the viral genome in the DRG.

[0214] In some embodiments, the nucleotide sequence encoding the miR binding site and / or the encoded miR binding site may be 20-75 nucleotides in length. In some embodiments, the nucleotide sequence encoding the miR binding site and / or the encoded miR binding site is 23 nucleotides in length. In some embodiments, the nucleotide sequence encoding the miR binding site and / or the encoded miR binding site is 71 nucleotides in length.

[0215] Non-limiting examples of nucleotide sequences encoding a miR binding site or binding si...

Claims

CLAIMSWe claim:

1. An adeno-associated virus (AAV) particle comprising an AAV capsid variant and a viral genome, wherein the viral genome comprises a frataxin (FXN) -encoding sequence and the AAV capsid variant comprises an amino acid sequence having the formula [N1]-[N2]-[N3] (SEQ ID NO: 4681) in loop VIII; wherein [N2] comprises the amino acid sequence of DWHR (SEQ ID NO: 4682); and wherein:(i) [Nl] comprises amino acids Xi, X2, X3, and X4. wherein X4is Q, K, E. S, P, R, N, or H; and / or(ii) [N3] comprises amino acids X5. X6, and X7, wherein X5is I, V, T. M, S. N, L, or F.

2. The AAV particle of claim 1, wherein the AAV capsid variant is an AAV9 capsid variant.

3. The AAV particle of claim 1 or claim 2, wherein the AAV capsid variant comprises an amino acid sequence that is at least 95% identical to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

4. The AAV particle of any one of claims 1-3, wherein loop VIII is present at amino acids comprising those corresponding to positions 580-599 of the amino acid sequence of SEQ ID NO: 981.

5. The AAV particle of any one of claims 1-4, wherein:(i) Xi is T, S, R, A. I. C, N, K, L, or Q;(ii) X2is N, T, G, V, S, Y, K, I, H, D, or F; and(iii) X3is T, N. K, D, I, S, P, A, Y, E, V, L, M. R, H, Q, or C.

6. The AAV particle of any one of claims 1-5, wherein:(i) X6is A, Y, P, N, S, T, G, E, V, W, F, or Q; and(ii) X7is Q, G, N, K, H, R, E, L, P, or M.

7. The AAV particle of any one of claims 1-6, wherein [Nl] comprises the amino acid sequence of TNTQ (SEQ ID NO: 4688).

8. The AAV particle of any one of claims 1-7. wherein [N3] comprises the amino acid sequence of IAQ.

9. The AAV particle of any one of claims 1-8. wherein [N1]-[N2]-[N3] comprises the ammo acid sequence of TNTQDWHRIAQ (SEQ ID NO: 343).

10. The AAV particle of any one of claims 1-9, wherein:(i) [Nl] is present at amino acids corresponding to positions 582-585 of the amino acid sequence of SEQ ID NO: 981;(ii) [N2] is present at amino acids corresponding to positions 586-589 of the amino acid sequence of SEQ ID NO: 981; and(iii) [N3] is present at amino acids corresponding to positions 590-592 of the amino acid sequence of SEQ ID NO: 981.

11. The AAV particle of any one of claims 1-10, wherein the AAV capsid variant further comprises [N4] comprising amino acids X8, X9, Xio, and Xn, wherein:(i) Xsis T, S, N. P. A, or I;(ii) X9is G, N. D, R. V, A. S. or Q;(iii) Xio is W, S, C. R, L. or G; and / or(iv) Xn is V, A, S, I, C, G, D, F. L, or T.

12. The AAV particle of claim 11, wherein [N4] comprises the amino acid sequence of TGWV (SEQ ID NO: 5066).

13. The AAV particle of claim 11 or claim 12. wherein [N4] is present at amino acids corresponding to positions 593-596 of the amino acid sequence of SEQ ID NO: 981.

14. The AAV particle of any one of claims 11-13, wherein [N1]-[N2]-[N3]-[N4] comprises the amino acid sequence of TNTQDWHRIAQTGWV (SEQ ID NO: 201).

15. An adcno-associatcd virus (AAV) particle comprising:(i) a viral genome comprising a frataxin (FXN)-encoding sequence; and(ii) an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to positions 203-736 of the amino acid sequence of SEQ ID NO: 981, wherein the AAV capsid variant comprises:T at an amino acid corresponding to position 584 of the amino acid sequence of SEQ ID NO: 981;D at an amino acid corresponding to position 586 of the amino acid sequence of SEQ ID NO: 981;W at an amino acid corresponding to position 587 of the amino acid sequence of SEQ ID NO: 981;H at an amino acid corresponding to position 588 of the amino acid sequence of SEQ ID NO:R at an amino acid corresponding to position 589 of the amino acid sequence of SEQ ID NO: 981; andI at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 981.

16. The AAV particle of any one of claims 1-15, wherein the AAV capsid variant comprises an amino acid sequence that is at least 95% identical to positions 138-736 of the amino acid sequence of SEQ ID NO: 981.

17. An adeno-associated virus (AAV) particle comprising:(i) a viral genome comprising a frataxin (FXN)-encoding sequence: and(ii) an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to positions 138-736 of the amino acid sequence of SEQ ID NO:

981. wherein the AAV capsid variant comprises:T at an amino acid corresponding to position 584 of the amino acid sequence of SEQ ID NO: 981;D at an amino acid corresponding to position 586 of the amino acid sequence of SEQ ID NO: 981;W at an amino acid corresponding to position 587 of the amino acid sequence of SEQ ID NO: 981;H at an amino acid corresponding to position 588 of the amino acid sequence of SEQ ID NO: 981;R at an amino acid corresponding to position 589 of the amino acid sequence of SEQ ID NO: 981; andI at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 981.

18. The AAV particle of any one of claims 1-17, wherein the AAV capsid variant comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 981.

19. An adeno-associated virus (AAV) particle comprising:(i) a viral genome comprising a frataxin (FXN)-encoding sequence: and(ii) an AAV capsid variant comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 981, wherein the AAV capsid variant comprises:T at an amino acid corresponding to position 584 of the amino acid sequence of SEQ ID NO: 981;D at an amino acid corresponding to position 586 of the amino acid sequence of SEQ ID NO:981;W at an amino acid corresponding to position 587 of the amino acid sequence of SEQ ID NO: 981;H at an amino acid corresponding to position 588 of the amino acid sequence of SEQ ID NO: 981;R at an amino acid corresponding to position 589 of the amino acid sequence of SEQ ID NO: 981; andI at an amino acid corresponding to position 590 of the amino acid sequence of SEQ ID NO: 981.

20. The adeno-associated virus (AAV) particle of claim 19, wherein the AAV capsid variant comprises:(i) an amino acid sequence that is at least 99% identical to the amino acid sequence of SEQ ID NO: 981;(ii) an amino acid sequence that is at least 99% identical to positions 138-736 of the amino acid sequence of SEQ ID NO: 981; and / or(iii) an amino acid sequence that is at least 99% identical to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

21. The AAV particle of any one of claims 15-20, wherein the AAV capsid variant comprises the amino acid sequence of TQDWHRI (SEQ ID NO: 941).

22. The AAV particle of any one of claims 15-21, wherein the AAV capsid variant comprises at least 8, at least 9, or at least 10 consecutive amino acids from the amino acid sequence of TNTQDWHRIAQ (SEQ ID NO: 343).

23. The AAV particle of any one of claims 15-22, wherein the AAV capsid variant comprises the amino acid sequence of TNTQDWHRIAQ (SEQ ID NO: 343) present at amino acids corresponding to positions 582-592 of the amino acid sequence of SEQ ID NO: 981.

24. The AAV particle of any one of claims 21-23, wherein the amino acid sequence of TQDWHRI (SEQ ID NO: 941) or TNTQDWHRIAQ (SEQ ID NO: 343) is present in loop VIII, wherein loop VIII comprises amino acids 580-599 of the amino acid sequence of SEQ ID NO: 981.

25. The AAV particle of any one of claims 1-24, wherein the AAV capsid variant comprises:(i) the amino acid sequence of SEQ ID NO: 981;(ii) the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQID NO: 981; and / or(iii) the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

26. The AAV particle of any one of claims 1-25, wherein the FXN-encoding sequence encodes a FXN protein that is not a cynomolgus monkey FXN protein.

27. The AAV particle of any one of claims 1-26, wherein the FXN-encoding sequence encodes a human FXN protein.

28. The AAV particle of claim 27, wherein the human FXN protein comprises(a) the amino acid sequence of SEQ ID NO: 1825 or an amino acid sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; or(b) the amino acid sequence of any one of SEQ ID NOs: 5124-5126 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%. at least 92%, at least 93%. at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; optionally, wherein the FXN protein is a wildtype human FXN protein.

29. The AAV particle of any one of claims 1-27. wherein the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g.. at least 80%, at least 85%, at least 90%, at least 91%. at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto.

30. The AAV particle of any one of claims 1-29. wherein the viral genome further comprises a promoter operably linked to the FXN-encoding sequence.

31. The AAV particle of claim 30, wherein the promoter comprises a human elongation factor la-subunit (EFla) promoter, a cytomegalovirus (CMV) immediate-early enhancer and / or promoter, a chicken 0- actin (CBA) promoter, a CAG promoter, a 0 glucuronidase (GUSB) promoter, a ubiquitin C (UBC) promoter, a neuron-specific enolase (NSE) promoter, a platelet-derived growth factor (PDGF) promoter, a platelet-derived growth factor B-chain (PDGF-0) promoter, a intercellular adhesion molecule 2 (ICAM- 2) promoter, a synapsin (Syn) promoter, a methyl-CpG binding protein 2 (MeCP2) promoter, a Ca2+ / calmodulin-dependent protein kinase II (CaMKII) promoter, a metabotropic glutamate receptor 2 (mGluR2) promoter, a neurofilament light chain (NFL) promoter, a neurofilament heavy' chain (NFH) promoter, a 0-globin minigene n02 promoter, a preproenkephalin (PPE) promoter, a enkephalin (Enk) and excitatory amino acid transporter 2 (EAAT2) promoter, a glial fibrillary acidic protein (GFAP) promoter, a myelin basic protein (MBP) promoter, a cardiovascular promoter (e.g., aMHC, cTnT, and CMV-MLC2k), a liver promoter (e.g., hAAT. TBG), a skeletal muscle promoter (e.g.. desmin. MCK,C512), or a functional fragment or truncation thereof.

32. The AAV particle of claim 30 or claim 31, wherein the promoter is a CMV promoter or CBA promoter, or a functional fragment or truncation of a CMV promoter or CBA promoter.

33. The AAV particle of claim 32, wherein the promoter is a truncated CBA promoter.

34. The AAV particle of claim 33, wherein the truncated CBA promoter is 50-400 nucleotides in length, e.g., 100-332 nucleotides in length.

35. The AAV particle of any one of claims 32-34, wherein the promoter comprises(i) the nucleotide sequence SEQ ID NO: 1738 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%. at least 97%. at least 98%, or at least 99% identical) thereto;(ii) the nucleotide sequence of SEQ ID NO: 1740 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; or(iii) the nucleotide sequence of SEQ ID NO: 1742 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

36. The AAV particle of claim 32, wherein the promoter is a truncated CMV promoter.

37. The AAV particle of claim 36, wherein the truncated CMV promoter is 50-300 nucleotides in length.

38. The AAV particle of claim 36 or claim 37, wherein the promoter comprises the nucleotide sequence of SEQ ID NO: 1750 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

39. The AAV particle of any one of claims 1-38, wherein the viral genome further comprises a nucleotide sequence encoding a miRNA (miR) binding site that modulates expression of the encoded FXN protein in a cell or tissue of the liver.

40. The AAV particle of claim 39, wherein the viral genome encodes 3 copies of the miR binding site.

41. The AAV particle of claim 40, wherein the 3 copies of the miR binding site are identical.

42. The AAV particle of any one of claims 39-41, wherein the miR binding site is a miR122 binding site.

43. The AAV particle of claim 42, wherein: the miR122 binding site is encoded by the nucleotide sequence of SEQ ID NO: 1827 or a nucleotide sequence comprising one, two. three, or up to four substitutions relative thereto; or the viral genome encodes 3 copies of the miR122 binding site, wherein the nucleotide sequence encoding the 3 copies of the miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence comprising one, two, three, four, five, six, seven, eight, nine, or up to ten substitutions relative thereto.

44. The AAV particle of any one of claims 1-43, wherein the viral genome further comprises at least one inverted terminal repeat (1TR) region.

45. The AAV particle of claim 44, wherein the at least one ITR region comprises an AAV2 ITR.

46. The AAV particle of claim 44 or claim 45. wherein the viral genome comprises a 5’ ITR region and a 3’ ITR region.

47. The AAV particle of claim 46, wherein the 5’ ITR region and 3’ ITR region are each an AAV2 ITR.

48. The AAV particle of claim 46 or claim 47. wherein: the 5' ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto; and / or the 3' ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

49. The AAV particle of any one of claims 1-48, wherein the viral genome further comprises an intron / exon region comprising an intron region and / or an exon region.

50. The AAV particle of claim 49, wherein the intron / exon region comprises: an immediate-early 1 (iel) intron region and / or a human beta-globin (hBglobin) intron 2 region; and / or an iel exon region and / or an hBglobin exon region.

51. The AAV particle of claim 49 or claim 50, wherein the intron region comprises:the nucleotide sequence of SEQ ID NO: 1819 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or the nucleotide sequence of SEQ ID NO: 1820 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto.

52. The AAV particle of any one of claims 49-51, wherein the exon region comprises: the nucleotide sequence of SEQ ID NO: 1817 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; and / or the nucleotide sequence of SEQ ID NO: 1821 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%. at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

53. The AAV particle of any one of claims 49-52, wherein the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto.

54. The AAV particle of any one of claims 1-53, wherein the viral genome further comprises a polyadenylation (poly A) region.

55. The AAV particle of claim 54, wherein the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

56. The AAV particle of any one of claims 1-35, or 39-55, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

57. The AAV particle of any one of claims 1-55, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

58. The AAV particle of any one of claims 1-55, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

59. The AAV particle of any one of claims 1-55, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

60. The AAV particle of any one of claims 1-27, wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) the FXN-encoding sequence, wherein the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g.. at least 80%, at least 85%. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and(iv) a 3’ ITR region.

61. The AAV particle of any one of claims 1-27. wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) the FXN-encoding sequence, wherein the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g.. at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iv) a nucleotide sequence encoding at least one miR122 binding site; and(v) a 3’ ITR region.

62. The AAV particle of any one of claims 1-27, wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) an intron / exon region;(iv) the FXN-encoding sequence, wherein the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%,at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(v) a nucleotide sequence encoding at least one miR122 binding site; and(vi) a 3‘ ITR region.

63. The AAV particle of any one of claims 1-27, wherein the viral genome comprises:(i) a 5’ inverted tenninal repeat (ITR) region;(ii) a promoter;(iii) an intron / exon region;(iv) the FXN-encoding sequence, wherein the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g., at least 80%, at least 85%, at least 90%, at least 91%. at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%. at least 98%, or at least 99% identical) thereto;(v) a nucleotide sequence encoding at least one miR122 binding site;(vi) a polyadenylation (poly A) region; and(vii) a 3’ ITR region.

64. The AAV particle of any one of claims 1-27. wherein the viral genome comprises:(i) a 5’ inverted terminal repeat (ITR) region;(ii) a promoter;(iii) an intron / exon region;(iv) the FXN-encoding sequence, wherein the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 80% identical (e.g.. at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(v) a nucleotide sequence encoding at least one miR122 binding site;(vi) a polyadenylation (poly A) region;(vii) a filler sequence; and(viii) a 3’ ITR region.

65. The AAV particle of claim 63 or claim 64, wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1742 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%. or at least 99% identical) thereto; and / or(vii) the 3’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto.

66. The AAV particle of claim 65, wherein the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1841 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.

67. The AAV particle of claim 63 or claim 64, wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1750 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or(vii) the 3’ 1TR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

68. The AAV particle of claim 67, wherein the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1840 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto, optionally wherein the filler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.

69. The AAV particle of claim 63 or claim 64. wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1738 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or(vii) the 3’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

70. The AAV particle of claim 69, wherein the viral genome further comprises a fdler sequence comprising the nucleotide sequence of SEQ ID NO: 1838 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto, optionally wherein the fdler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.

71. The AAV particle of claim 63 or claim 64. wherein:(i) the 5’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1811 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1740 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(iii) the intron / cxon region comprises the nucleotide sequence of SEQ ID NO: 1816 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or(vii) the 3’ ITR region comprises the nucleotide sequence of SEQ ID NO: 1812 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

72. The AAV particle of claim 71, wherein the viral genome further comprises a fdler sequence comprising the nucleotide sequence of SEQ ID NO: 1839 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto, optionally wherein the fdler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR.

73. The AAV particle of any one of claims 1-27, wherein the viral genome comprises:(i) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iii) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; or(iv) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto.

74. The AAV particle of any one of claims 63-65, wherein:(i) the 5' ITR region comprises the nucleotide sequence of SEQ ID NO: 1811;(ii) the promoter comprises the nucleotide sequence of SEQ ID NO: 1742;(iii) the intron / exon region comprises the nucleotide sequence of SEQ ID NO: 1816;(iv) the FXN-encoding sequence comprises the nucleotide sequence of SEQ ID NO: 1824;(v) the nucleotide sequence encoding the at least one miR122 binding site comprises the nucleotide sequence of SEQ ID NO: 1826;(vi) the poly A region comprises the nucleotide sequence of SEQ ID NO: 1828; and(vii) the 3' ITR region comprises the nucleotide sequence of SEQ ID NO: 1812.

75. The AAV particle of claim 74, wherein the viral genome further comprises a filler sequence comprising the nucleotide sequence of SEQ ID NO: 1841, wherein the filler sequence is positioned 3’ to the poly A region and 5’ to the 3’ ITR region.

76. The AAV particle of any one of claims 1-35, 39-56, 63-66, or 73-75, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1797.

77. The AAV particle of any one of claims 1-35, 39-56, 63-66. or 73-76, wherein the viral genome consists of the nucleotide sequence of SEQ ID NO: 1797.

78. An adeno-associated virus (AAV) particle comprising an AAV capsid variant and a viral genome comprising a frataxin (FXN)-encoding sequence, wherein the AAV capsid variant comprises:(i) the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(ii) the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and / or(iii) the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and wherein the viral genome comprises:(a) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(b) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto;(c) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; or(d) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%. at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto.

79. An adeno-associated virus (AAV) particle comprising a viral genome comprising the nucleotide sequence of SEQ ID NO: 1824 and an AAV capsid variant comprising die amino acid sequence of SEQ ID NO: 981, die amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981, and / or the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

80. The AAV particle of claim 78 or claim 79, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1797.

81. The AAV particle of claims 1-80. wherein the viral genome is single-stranded.

82. A cell comprising the AAV particle of any one of claims 1-81, optionally wherein the cell is a mammalian cell (e.g., an HEK293 cell), an insect cell (e.g., an SP9 cell), or a bacterial cell.

83. A method of making an AAV particle of any one of claims 1-81, wherein the method comprises:(i) providing a cell comprising the viral genome comprising a frataxin (FXN)-encoding sequence and a nucleic acid encoding the AAV capsid variant: and(ii) incubating the cell under conditions suitable to encapsulate the viral genome in the AAV capsid variant; thereby making the AAV particle.

84. The method of claim 83, wherein the viral genome comprises(i) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence drat is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(ii) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto;(iii) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; or(iv) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%. at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto; and wherein the AAV capsid variant comprises(a) the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(b) the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto: and / or(c) the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981 or an amino acid sequence that is at least 90% identical (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%. at least 98%, or at least 99% identical) thereto.

85. The method of claim 83, wherein the viral genome comprises(i) the nucleotide sequence of SEQ ID NO: 1797 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%. at least 94%, at least 95%. at least 96%, at least 97%, at least 98%. or at least 99% identical) thereto;(ii) the nucleotide sequence of SEQ ID NO: 1801 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%. at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto;(iii) the nucleotide sequence of SEQ ID NO: 1808 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; or(iv) the nucleotide sequence of SEQ ID NO: 1809 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and wherein the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 981, the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981, and / or the amino acid sequence according to positions 203-736 of tire ammo acid sequence of SEQ ID NO: 981.

86. The method of claim 83, wherein the viral genome comprises the nucleotide sequence of SEQ ID NO: 1797 and the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 981, the amino acid sequence according to positions 138-736 of the amino acid sequence of SEQ ID NO: 981, and / or the amino acid sequence according to positions 203-736 of the amino acid sequence of SEQ ID NO: 981.

87. The method of any one of claims 83-86, further comprising, prior to step (i), introducing a nucleic acid comprising the viral genome into the cell.

88. The method of any one of claims 83-87, further comprising, prior to step (i), introducing the nucleic acid encoding the AAV capsid variant into the cell.

89. The method of any one of claims 83-88, wherein the cell comprises a mammalian cell (e g., an HEK293 cell), an insect cell (e.g., an S19 cell), or a bacterial cell.

90. A pharmaceutical composition comprising the AAV particle of any one of claims 1-81 and a pharmaceutically acceptable excipient.

91. A method of delivering an AAV particle encoding a frataxin (FXN) protein to a cell, comprising administering an effective amount of the pharmaceutical composition of claim 90 or the AAV particle of any one of claims 1-81.

92. The method of claim 91, wherein the cell is in a subject.

93. The method of claim 92, wherein the subject has. has been diagnosed with having, or is at risk of having a disorder associated with FXN deficiency or at least one symptom thereof.

94. The method of claim 93, wherein the disorder is Friedreich’s Ataxia (FA).

95. A method of treating a subject having or diagnosed with having a disorder associated with frataxin (FXN) deficiency or at least one sy mptom thereof, comprising administering to the subject an effective amount of the pharmaceutical composition of claim 90 or the AAV particle of any one of claims 1-81.

96. The method of claim 95, wherein the subject has, has been diagnosed with having, or is at risk of having Friedreich’s Ataxia (FA) or at least one symptom thereof.

97. A method of treating a subject having or diagnosed with having a disorder or at least one symptom thereof, wherein the disorder is Friedreich’s Ataxia (FA), comprising administering to the subject an effective amount of the pharmaceutical composition of claim 90 or the AAV particle of any one of claims 1-81.

98. The method of any one of claims 95-97. wherein the treating results in prevention of progression of the disorder or at least one symptom thereof in the subject.

99. The method of any one of claims 95-98, wherein the treating results in amelioration of at least one symptom of the disorder.

100. The method of any one of claims 93-99, wherein the at least one symptom comprises impaired sensory functions, impaired motor function (e.g., ataxia and / or involuntary movements), fatigue, chronic pain, seizures, impaired speech, sleep disturbances, metabolic disorders (e.g., diabetes), and / or increased spasticity.

101. The method of any one of claims 93-100, wherein the treating stabilizes, slows the progression of. or improves the subject’s disorder as determined by the modified Friedreich Ataxia Rating Scale (mFARS), the Scale for the Assessment and Rating of Ataxia (SARA), and / or the International Cooperative Ataxia Rating Scale (I CARS).

102. The method of claim 101, wherein the treating slows the subject’s progression of the disorder as measured by mFARS, SARA, and / or ICARS relative to an individual with the disorder who has not been administered the pharmaceutical composition or the AAV particle.

103. The method of any one of claims 92-102. wherein the subject is a human.

104. The method of any one of claims 92-103, wherein the AAV particle or the pharmaceutical composition is delivered to a cell or tissue of the of the central nervous system (CNS) in the subject.

105. The method of claim 104, wherein the cell or tissue of the CNS is a cell or tissue of the amy gdala, brainstem, caudate, central grey, cerebellum (c.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region).

106. The method of any one of claims 92-105, wherein the AAV particle or the pharmaceutical composition is delivered to the subject via intravenous administration.

107. The method of any one of claims 92-106, further comprising evaluating, e.g., measuring, the level of FXN expression, e.g., FXN gene expression, FXN mRNA expression, and / or FXN protein expression, in the subject, e.g.. in a cell, tissue, or fluid of the subject.

108. The method of claim 107, wherein the level of FXN protein expression is measured by an enzyme- linked immunosorbent assay (ELISA), a Western blot, an immunohistochemistry assay, or a frataxin biofluid assay.

109. The method of claim 107 or claim 108. wherein evaluating the subject’s level of FXN expression is performed before and / or after administration of the pharmaceutical composition or AAV particle, optionally wherein the subject’s level of FXN expression before administration is compared to the subject’s level of FXN expression after administration.

110. The method of any one of claims 107-109, comprising evaluating the level of FXN expression in a cell or tissue of the CNS.

111. The method of claim 110, wherein the cell or tissue of the CNS is a cell or tissue of the amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus. gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region).

112. The method of any one of claims 107-109, comprising evaluating the level of FXN expression, e.g., FXN gene, FXN mRNA, and / or FXN protein expression, in a peripheral cell or tissue of the subject.

113. The method of claim 112, wherein the peripheral cell or tissue is a cell or tissue of the heart and / or muscle.

114. The method of claim 113, wherein the muscle is skeletal muscle.

115. The method of any one of claims 107-114, wherein the subject’s level of FXN protein expression after administration is increased relative to the subject’s level of FXN protein expression before administration.

116. The method of any one of claims 107-115, further comprising evaluating, e.g., measuring, the level of FXN protein activity in the subject.

117. The method of any one of claims 92-116, wherein administering the pharmaceutical composition or AAV particle to tire subject results in an increase in:(i) the level of FXN protein or FXN gene expression in a cell, tissue, (e.g., a cell or tissue of the CNS, e.g.. amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region), or a cell or tissue outside of the CNS, e.g., muscle (e.g., skeletal muscle)), and / or fluid (e.g., CSF and or serum), of the subject relative to baseline and / or relative to the level of FXN protein or FXN gene expression in a cell, tissue, or fluid of an individual with a disorder associated with FXN deficiency who has not been administered the pharmaceutical composition or AAV particle;(ii) the number and / or level of viral genomes (VG) per cell in a CNS tissue (e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus. gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus. oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region)) or non-CNS tissue (e.g.. muscle (e.g., skeletal muscle)) of the subject relative to the number and / or level of VG per cell in a peripheral tissue of the subject; and / or(iii) the level of FXN activity in a cell, tissue, (e.g., a cell or tissue of the CNS, e.g., amygdala, brainstem, caudate, central grey, cerebellum (e.g., Purkinje cell layer and deep cerebellar nuclei), cortex (e.g., frontal cortex, motor cortex, perirhinal cortex, sensory’ cortex, temporal cortex), external cuneate nucleus, geniculate nucleus, globus pallidus, gracile nucleus, hippocampus, inferior colliculus, inferior olivary complex, nucleus ambiguus, oculomotor nucleus, putamen, substantia nigra, thalamus, ventral palladium, vestibular nucleus, and / or spinal cord (e.g., cervical spinal cord region, lumbar spinal cord region, or thoracic spinal cord region)), or a cell or tissue outside of the CNS, e.g., muscle (e.g., skeletal muscle)), and / or fluid (e.g.., CSF and or serum) of the subject relative to baseline and / or relative to FXN activity in a cell, tissue, or fluid of an individual with a disorder associated with FXN deficiency who has not been administered the pharmaceutical composition or AAV particle.

118. The method of any one of claims 93-117, further comprising administering to the subject at least one additional agent and / or therapy.

119. The method of claim 118, wherein the at least one additional agent and / or therapy comprises an agent and / or therapy suitable for treating the disorder associated with FXN deficiency (e.g., Friedreich's Ataxia).

120. The method of claim 118 or claim 119. wherein the at least one additional agent and / or therapy comprises omaveloxolone or idebenone.

121. The method of any one of claims 92-120, further comprising administering an immunosuppressant to the subject.

122. The method of claim 121. wherein the immunosuppressant comprises a corticosteroid (e.g.. prednisone, prednisolone, methylprednisolone, and / or dexamethasone), rapamycin, mycophenolate mofetil. tacrolimus, rituximab, and / or eculizumab hydroxychloroquine.

123. The pharmaceutical composition of claim 90 or the AAV particle of any one of claims 1-81 for use in a method of treating a disorder according to any one of claims 94-122.

124. The pharmaceutical composition of claim 90 or the AAV particle of any one of claims 1-81 for use in the treatment of a disorder associated with FXN deficiency, or at least one symptom thereof, in a subject, optionally wherein the disorder is Friedreich’s Ataxia (FA).

125. The pharmaceutical composition or the AAV particle of claim 124, wherein the subject has, has been diagnosed with having, or is at risk of having FA.

126. Use of the pharmaceutical composition of claim 90 or the AAV particle of any one of claims 1-81 in the manufacture of a medicament for the treatment of a disorder associated with FXN deficiency, or at least one symptom th ere of. in a subject, optionally wherein the disorder is Friedreich’s Ataxia (FA).

127. The use of claim 126, wherein the subject has, has been diagnosed with having, or is at risk of having FA.

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