Compositions and methods for treating glycogen storage disease type 1a

Abstract

The invention provides compositions comprising novel adenosine base editors (e.g., ABE8) that have increased efficiency and methods of using base editors comprising adenosine deaminase variants for altering mutations associated with Glycogen Storage Disease Type 1a (GSD1a).

Description

CROSS REFERENCE TO RELATED APPLICATIONS 5          This application is an International PCT application which claims priority to and benefit of U.S. Provisional Application Nos. 62 / 805,271, filed February 13, 2019; 62 / 852,228, filed May 23, 2019; 62 / 852,224, filed May 23, 2019; 62 / 876,354, filed July 19, 2019; 62 / 912,992, filed October 9, 2019; 62 / 931,722, filed November 6, 2019; 62 / 941,569, filed November 27, 2019; and 62 / 966,526, filed January 27, 2020, the contents of all of 0 which are incorporated by reference herein in their entireties. BACKGROUND For most known genetic diseases, correction of a point mutation in the target locus, rather than stochastic disruption of the gene, is needed to study or address the underlying 15 cause of the disease. Current genome editing technologies utilizing the clustered regularly interspaced short palindromic repeat (CRISPR) system introduce double-stranded DNA breaks at a target locus as the first step to gene correction. In response to double-stranded DNA breaks, cellular DNA repair processes mostly result in random insertions or deletions (indels) at the site of DNA cleavage through non-homologous end joining. Although most 20 genetic diseases arise from point mutations, current approaches to point mutation correction are inefficient and typically induce an abundance of random insertions and deletions (indels) at the target locus resulting from the cellular response to dsDNA breaks. Therefore, there is a need for an improved form of genome editing that is more efficient and with far fewer undesired products such as stochastic insertions or deletions (indels) or translocations. 25         Glycogen Storage Disease Type 1 (also known as GSD1 or Von Gierke Disease) is an inherited disorder that results in a deficiency in glycogenolysis and gluconeogenesis, with accumulation of glycogen and lipids in tissues, causing life-threatening hypoglycemia and lactic acidosis and leading to potential CNS damage and long-term liver and renal complications, such as steatosis, hepatic adenomas and hepatocellular carcinomas. 30         There are two types of GSD1, Type 1a (GSD1a) and Type 1b (GSD1b), which are caused by different genetic mutations. GSD1a is caused by a mutation in the glucose-6-phosphatase (G6PC) gene and affects about 80% of patients with GSD1. About one in 2020221355   24 Apr 2026 100,000 newborns in the US have GSD1a with about 22% of patients carrying the recessive mutation Q347* and 37% of patients carrying the recessive mutation R83C. There are no drug therapies approved for GSD1a. Although liver transplants are curative, there are no approved therapies and the current treatment regimen involves nearly 5 continuous cornstarch feeding. If chronically untreated, patients develop severe lactic acidosis, can progress to renal failure, and die in infancy or childhood. GSD1a is an area of significant unmet medical need. Therefore, there is a need for novel compositions and methods for treating patients with GSD1a. INCORPORATION BY REFERENCE All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. Absent any indication otherwise, publications, patents, and patent applications mentioned in this specification are incorporated herein by reference in their entireties. 15 SUMMARY In one particular aspect, the invention encompasses a method of editing a glucose-6-phosphatase (G6PC) polynucleotide comprising a single nucleotide polymorphism (SNP) associated with Glycogen Storage Disease Type 1a (GSD1a), the method comprising 20 contacting the G6PC polynucleotide with an Adenosine Deaminase Base Editor 8 (ABE8) in a complex with one or more guide polynucleotides, wherein the ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference 25 amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group 30 consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and wherein one or more of said guide polynucleotides target said base editor to effect an A»T to G^C alteration of the SNP associated with GSDla. In one other aspect, the invention encompasses a cell comprising: 2020221355   24 Apr 2026 an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, wherein said Adenosine Deaminase Base Editor 8 (ABE8) comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant 5 comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; and one or more guide polynucleotides that target the base editor to effect an A»T to G*C alteration of the SNP associated with GSD1a, with the proviso that the cell is not a human ovum, a human zygote cell, a human embryo cell, or a human totipotent cell. 15          In one other aspect, the invention encompasses a method of treating GSD1a in a subject comprising administering to said subject: an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, wherein said ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain 20 comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine 25 deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; and one or more guide polynucleotides that target the ABE8 to effect an A»T to G»C alteration of the SNP associated with GSD1a, with the proviso that said administration is not made to a human ovum, a human zygote, a human embryo, or a human totipotent cell. 30          In one other aspect, the invention encompasses a method of producing a hepatocyte, or progenitor thereof, the method comprising: (a) introducing into an induced pluripotent stem cell or hepatocyte progenitor comprising a SNP associated with GSD1a: an Adenosine Deaminase Base Editor 8 (ABE8), 2020221355   24 Apr 2026 or a polynucleotide encoding the ABE8, wherein the base editor comprises a polynucleotide-programmable nucleotide-binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid 5 sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group 0 consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; and one or more guide polynucleotides, wherein the one or more guide polynucleotides target the base editor to effect an A«T to G rC alteration of the SNP associated with GSD1a; and (b) differentiating the induced pluripotent stem cell into a hepatocyte or 15 progenitor thereof. In one other aspect, the invention encompasses a method of editing a glucose-6-phosphatase (G6PC) polynucleotide comprising a single nucleotide polymorphism (SNP) associated with Glycogen Storage Disease Type 1a (GSD1a), the method comprising contacting the G6PC polynucleotide with an Adenosine Deaminase Base Editor 8 (ABE8) in 20 a complex with one or more guide polynucleotides, wherein the ABE8 comprises an adenosine deaminase domain inserted within a Cas9 or a Cas12 polypeptide, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: 25 MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid 30 sequence, and wherein one or more of said guide polynucleotides target said base editor to effect an A«T to (rC alteration of the SNP associated with GSDla. In one other aspect, the invention encompasses a method of treating Glycogen Storage Disease Type 1a (GSD1a) in a subject, the method comprising administering to said subject: 2020221355   24 Apr 2026 an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, wherein said ABE8 comprises an adenosine deaminase domain inserted within a Cas9 or Cas12 polypeptide, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical 5 to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group 0 consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; and one or more guide polynucleotides that target the ABE8 to effect an A•T to G*C alteration of a SNP associated with GSDla, thereby treating GSDla in the subject, with the proviso that said administration is not made to a human ovum, a human zygote, a human embryo, or a human totipotent cell. 15          In one other aspect, the invention encompasses a method for treating Glycogen Storage Disease Type 1a (GSD1a) in a subject, the method comprising administering to the subject: a fusion protein comprising an adenosine deaminase domain inserted within a Cas9 or a Cas12 polypeptide, or a polynucleotide encoding said fusion protein, wherein the adenosine 20 deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine 25 deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; and one or more guide polynucleotides to target the fusion protein to effect an A*T to G»C alteration of a single nucleotide polymorphism (SNP) associated with GSD1a, thereby treating GSD1a in the subject, with the proviso that said administration is not made to a 30 human ovum, a human zygote, a human embryo, or a human totipotent cell. In one other aspect, the invention encompasses a pharmaceutical composition for the treatment of Glycogen Storage Disease Type 1a (GSD1a) comprising an effective amount of an Adenosine Deaminase Base Editor 8 (ABE8), wherein said ABE8 comprises a 2020221355   24 Apr 2026 polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: 5 MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid 0 sequence. In one other aspect, the invention encompasses a pharmaceutical composition for the treatment of Glycogen Storage Disease Type 1a (GSD1a) comprising an effective amount of the cell of any one of the preceding aspects. In one other aspect, the invention encompasses a kit for the treatment of Glycogen 15 Storage Disease Type 1a (GSD1a), the kit comprising an Adenosine Deaminase Base Editor 8 (ABE8), wherein said ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: 20 MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid 25 sequence, and one or more guide polynucleotides that are capable of targeting the ABE8 to effect an A*T to (rC alteration of a SNP associated with GSDla. In one other aspect, the invention encompasses a kit for the treatment of Glycogen Storage Disease Type 1a (GSD1a), the kit comprising the cell of any one of the preceding aspects. 30          In one other aspect, the invention encompasses a base editor system comprising an Adenosine Deaminase Base Editor 8 (ABE8) in a complex with one or more guide polynucleotides, wherein the ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain 2020221355   24 Apr 2026 comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP 5 GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and wherein one or more of said guide polynucleotides target said base editor to effect an A*T to (rC alteration of the SNP associated with GSDla. 0          In one other aspect, the invention encompasses a base editor system comprising one or more guide RNAs and a fusion protein comprising a polynucleotide programmable DNA binding domain comprising an amino acid sequence with at least 90% identity to the following sequence: DKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATR 15 LKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDE VAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQ LVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLT PNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTE ITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFY 20 KFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKD NREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTN FDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKV TVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVL TLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFL 25 KSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVD ELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV 30 GTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANG EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSD KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR 2020221355   24 Apr 2026 EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL GGD, and at least one base editor domain comprising an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNR 5 AIGLHDPTAHAEIMALRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNA KTGAAGSLMDVLHYPGMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and wherein one or more of said guide polynucleotides target said base 0 editor to effect an A»T to G^C alteration of the SNP associated with GSDla. In one aspect, the invention encompasses a cell comprising the base editor system of any one of the preceding aspects, with the proviso that the cell is not a human ovum, a human zygote cell, a human embryo cell, or a human totipotent cell. General aspects of the present disclosure are also provided herein. These are set out 15 below and in the description that follows. The present disclosure features compositions and methods for the precise correction of pathogenic amino acids using a programmable nucleobase editor. In particular, the compositions and methods of the disclosure are useful for the treatment of Glycogen Storage Disease Type 1a (GSD1a). Thus, the disclosure provides compositions and methods for 20   treating GSD1a using an adenosine (A) base editor (ABE) (e.g., ABE8) to precisely correct a single nucleotide polymorphism in the endogenous G6PC gene to correct a deleterious mutation (e.g., Q347X, R83C). In one aspect, the disclosure provides a method of editing a G6PC polynucleotide comprising a single nucleotide polymorphism (SNP) associated with Glycogen Storage 25 Disease Type 1a (GSD1a), the method comprising contacting the G6PC polynucleotide with an Adenosine Deaminase Base Editor 8 (ABE) in complex with one or more guide polynucleotides, wherein the ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, and wherein one or more of the guide polynucleotides target the base editor to effect an A»T to G^C alteration of the SNP 30 associated with GSD1a. In another aspect, the disclosure provides a cell comprising an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, comprising a polynucleotide programmable DNA binding domain and an adenosine deaminase domain; and one or more guide polynucleotides that target the base editor to effect 2020221355   24 Feb 2026 an A»T to G^C alteration of the SNP associated with GSDla. In another aspect, the disclosure provides a method of treating GSD1a in a subject comprising administering to said subject: an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, to said subject, wherein said Adenosine Deaminase Base Editor 8 (ABE8) 5 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain; and one or more guide polynucleotides that target the Adenosine Deaminase Base Editor 8 (ABE8) to effect an A*T to G*C alteration of the SNP associated with GSD1a. In another aspect, the disclosure provides a method of producing a hepatocyte, or progenitor thereof, the method comprising: a) introducing into an induced pluripotent stem cell or 10 hepatocyte progenitor comprising an SNP associated with GSD1a, an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding the Adenosine Deaminase Base Editor 8 (ABE8), wherein the base editor comprises a polynucleotide-programmable nucleotide-binding domain and an adenosine deaminase domain; and one or more guide polynucleotides, wherein the one or more guide polynucleotides target the base editor to effect an A*T to G»C 15 alteration of the SNP associated with GSD1a; and b) differentiating the induced pluripotent stem cell or hepatocyte progenitor into hepatocyte. In one aspect, the disclosure provides a method of editing a glucose-6-phosphatase (G6PC) polynucleotide comprising a single nucleotide polymorphism (SNP) associated with Glycogen Storage Disease Type 1a (GSD1a), the method comprising contacting the G6PC 20 polynucleotide with an Adenosine Deaminase Base Editor 8 (ABE8) in a complex with one or more guide polynucleotides, wherein the Adenosine Deaminase Base Editor 8 (ABE8) comprises an adenosine deaminase variant domain inserted within a Cas9 or a Cas12 polypeptide, and wherein one or more of said guide polynucleotides target said base editor to effect an A«T to G^C alteration of the SNP associated with GSD1a. In another aspect, the 25 disclosure provides a method of treating Glycogen Storage Disease Type 1a (GSD1a) in a subject, the method comprising administering to said subject: an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, to said subject, wherein said Adenosine Deaminase Base Editor 8 (ABE8) comprises an adenosine deaminase variant inserted within a Cas9 or Cas12 polypeptide; and one or more guide polynucleotides that 30 target the Adenosine Deaminase Base Editor 8 (ABE8) to effect an A»T to G•C alteration of a SNP associated with GSD1a, thereby treating GSD1a in the subject. In yet another aspect, the disclosure provides, a method for treating Glycogen Storage Disease Type 1a (GSD1a) in a subject, the method comprising administering to the subject: a fusion protein comprising an 2020221355   24 Feb 2026 adenosine deaminase variant inserted within a Cas9 or a Cas12 polypeptide, or a polynucleotide encoding the fusion protein thereof; and one or more guide polynucleotides to target the fusion protein to effect an A*T to G<" alteration of a single nucleotide polymorphism (SNP) associated with GSD1a, thereby treating GSD1a in the subject. 5          In an aspect, the disclosure provides a pharmaceutical composition for the treatment of Glycogen Storage Disease Type 1a (GSD1a) comprising an effective amount of an Adenosine Deaminase Base Editor 8 (ABE8), wherein said Adenosine Deaminase Base Editor 8 (ABE8) comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase variant domain. In some embodiments, the pharmaceutical composition 10 includes one or more guide polynucleotides that are capable of targeting the Adenosine Deaminase Base Editor 8 (ABE8) to effect an A*T to G^C alteration of a SNP associated with GSD1a. In another aspect, the disclosure provides a pharmaceutical composition for the treatment of Glycogen Storage Disease Type 1a (GSD1a) comprising an effective amount of any of the cells provided herein. In some embodiments, the pharmaceutical composition 15 includes a comprising a pharmaceutically acceptable excipient. In another aspect, the disclosure provides a kit for the treatment of Glycogen Storage Disease Type 1a (GSD1a), the kit comprising an Adenosine Deaminase Base Editor 8 (ABE8), wherein said Adenosine Deaminase Base Editor 8 (ABE8) comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, 20 and one or more guide polynucleotides that are capable of targeting the Adenosine Deaminase Base Editor 8 (ABE8) to effect an A»T to G^C alteration of a SNP associated with GSD1a. In yet another aspect, the disclosure provides a kit for the treatment of Glycogen Storage Disease Type 1a (GSD1a), the kit comprising any of the cells provided herein. In some embodiments, the contacting is in a cell, a eukaryotic cell, a mammalian cell, 25 or a human cell. In some embodiments, the cell is in vivo. In some embodiments, the cell is ex vivo. In some embodiments, the cell is a hepatocyte, a hepatocyte precursor, or an iPSc-derived hepatocyte. In some embodiments, the cell expresses a G6PC polypeptide. In some embodiments, the cell or hepatocyte progenitor is from a subject having GSD1a. In some embodiments, the subject is a mammal or a human. In some embodiments, the hepatocyte or 30 hepatocyte progenitor is a mammalian cell or human cell. In some embodiments, the Adenosine Deaminase Base Editor 8 (ABE8), or polynucleotide encoding said Adenosine Deaminase Base Editor 8 (ABE8), and said one or more guide polynucleotides is delivered to a cell of the subject. 2020221355   24 Feb 2026 In various embodiments of the above aspects or any other aspect of the disclosure delineated herein, the SNP associated with GSD1a is located in the glucose-6-phosphatase (G6PC) gene. In one embodiment, the A*T to G*C alteration at the SNP associated with Glycogen Storage Disease Type 1a (GSD1a) changes a glutamine (Q) to a non-glutamine (X) 5 amino acid. In one embodiment, the A*T to G•C alteration at the SNP associated with Glycogen Storage Disease Type 1a (GSD1a) changes an arginine (R) to a non-arginine (X) in the G6PC polypeptide. In one embodiment, the SNP associated with GSD1a results in expression of an G6PC polypeptide having a non-glutamine (X) amino acid at position 347 or a non-arginine (X) amino acid at position 83. In one embodiment, the base editor correction 10 replaces the non-glutamine amino acid (X) at position 347 with a glutamine. In another embodiment, the base editor correction replaces the non-arginine amino acid (X) at position 83 with an arginine. In one embodiment, the A*T to G*C alteration at the SNP associated with GSD1a results in expression of a G6PC polypeptide that prematurely terminates at amino acid position 347 or encodes a cysteine at position 83. In some embodiments, the 15 alteration at the SNP is one or more of Q347X and / or R83C. In various embodiments of the above aspects or any other aspect of the disclosure delineated herein, the adenosine deaminase variant is inserted within a flexible loop, an alpha helix region, an unstructured portion, or a solvent accessible portion of the Cas9 or Cas12 polypeptide. In some embodiments, the adenosine deaminase variant is flanked by a N- 20 terminal fragment and a C-terminal fragment of the Cas9 or Cas12 polypeptide. In some embodiments, the fusion protein or Adenosine Deaminase Base Editor 8 (ABE8) comprises the structure NH2-[N-terminal fragment of the Cas9 or Cas12 polypeptide]-[adenosine deaminase variant]-[C-terminal fragment of the Cas9 or Cas12 polypeptide]-COOH, wherein each instance of “]-[“ is an optional linker. In one embodiment, the C-terminus of the N 25 terminal fragment or the N-terminus of the C terminal fragment comprises a part of a flexible loop of the Cas9 or the Cas12 polypeptide. In one embodiment, the flexible loop comprises an amino acid in proximity to a target nucleobase. In some embodiments, the one or more guide polynucleotides direct the fusion protein or Adenosine Deaminase Base Editor 8 (ABE8) to effect deamination of a target nucleobase. In some embodiments, the deamination 30 of the SNP target nucleobase replaces the target nucleobase with a non-wild type nucleobase, and wherein the deamination of the target nucleobase ameliorates symptoms of GSD1a. In one embodiment, the target nucleobase is 1-20 nucleobases away from a PAM sequence in 2020221355   24 Feb 2026 the target polynucleotide sequence. In one embodiment, the target nucleobase is 2-12 nucleobases upstream of the PAM sequence. In one embodiment, the N-terminal fragment or the C-terminal fragment of the Cas9 or Cas12 polypeptide binds the target polynucleotide sequence. In one embodiment, the N- 5 terminal fragment or the C-terminal fragment comprises a RuvC domain; the N-terminal fragment or the C-terminal fragment comprises a HNH domain; neither of the N-terminal fragment and the C-terminal fragment comprises an HNH domain; or neither of the N-terminal fragment and the C-terminal fragment comprises a RuvC domain. In one embodiment, the Cas9 or Cas12 polypeptide comprises a partial or complete deletion in one 10 or more structural domains and wherein the deaminase is inserted at the partial or complete deletion position of the Cas9 or Cas12 polypeptide. In one embodiment, the deletion is within a RuvC domain; the deletion is within an HNH domain; or the deletion bridges a RuvC domain and a C-terminal domain, a L-I domain and a HNH domain, or a RuvC domain and a L-I domain. 15         In various embodiments, the polynucleotide programmable DNA binding domain is a Cas9 polypeptide. In some embodiments, the fusion protein or Adenosine Deaminase Base Editor 8 (ABE8) comprises an adenosine deaminase variant domain inserted in a Cas9 polypeptide. In some embodiments, the Cas9 polypeptide is a Streptococcus pyogenes Cas9 (SpCas9), Staphylococcus aureus Cas9 (SaCas9), Streptococcus thermophilus 1 Cas9 20 (St1Cas9), or variants thereof. In some embodiments, the Cas9 polypeptide the following amino acid sequence (Cas9 reference sequence): MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI 25 QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT 30 NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV 2020221355   24 Feb 2026 DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAyLNAV 5 VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKE SIL PKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI 10 REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD (single underline: HNH domain; double underline: RuvC domain; (Cas9 reference sequence), or a corresponding region thereof. In some embodiments, the Cas9 polypeptide comprises a deletion of amino acids 1017-1069 as numbered in the Cas9 polypeptide reference sequence or corresponding amino 15 acids thereof; the Cas9 polypeptide comprises a deletion of amino acids 792-872 as numbered in the Cas9 polypeptide reference sequence or corresponding amino acids thereof; or the Cas9 polypeptide comprises a deletion of amino acids 792-906 as numbered in the Cas9 polypeptide reference sequence or corresponding amino acids thereof. In some embodiments, the adenosine deaminase variant is inserted within a flexible loop of the Cas9 20 polypeptide. In some embodiments, the flexible loop comprises a region selected from the group consisting of amino acid residues at positions 530-537, 569-579, 686-691, 768-793, 943-947, 1002-1040, 1052-1077, 1232-1248, and 1298-1300 as numbered in the Cas9 reference sequence, or corresponding amino acid positions thereof. In some embodiments, the deaminase is inserted between amino acid positions 768-769, 791-792, 792-793, 1015 25   1016, 1022-1023, 1026-1027, 1029-1030, 1040-1041, 1052-1053, 1054-1055, 1067-1068, 1068-1069, 1247-1248, or 1248-1249 as numbered in the Cas9 reference sequence, or corresponding amino acid positions thereof. In some embodiments, the deaminase is inserted between amino acid positions 768-769, 792-793, 1022-1023, 1026-1027, 1040-1041, 10681069, or 1247-1248 as numbered in the Cas9 reference sequence or corresponding amino acid 30 positions thereof. In some embodiments, the deaminase is inserted between amino acid positions 1016-1017, 1023-1024, 1029-1030, 1040-1041, 1069-1070, or 1247-1248 as numbered in the Cas9 reference sequence or corresponding amino acid positions thereof. In some embodiments, the adenosine deaminase variant is inserted within the Cas9 polypeptide 2020221355   24 Feb 2026 at the loci identified in Table 10A. In some embodiments, the N-terminal fragment comprises amino acid residues 1-529, 538-568, 580-685, 692-942, 948-1001, 1026-1051, 1078-1231, and / or 1248-1297 of the Cas9 reference sequence, or corresponding residues thereof. In some embodiments, the C-terminal fragment comprises amino acid residues 5   1301-1368, 1248-1297, 1078-1231, 1026-1051, 948-1001, 692-942, 580-685, and / or 538-568 of the Cas9 reference sequence, or corresponding residues thereof. In some embodiments, the Cas9 polypeptide is a nickase or wherein the Cas9 polypeptide is nuclease inactive. In some embodiments, the Cas9 polypeptide is a modified SpCas9 and has specificity for an altered PAM or specificity for a non-G PAM. In some 10 embodiments, the modified SpCas9 polypeptide includes amino acid substitutions D1135M, S1136Q, G1218K, E1219F, A1322R, D1332A, R1335E, and T1337R (SpCas9- MQKFRAER) and has specificity for the altered PAM 5’-NGC-3’. In various embodiments, the polynucleotide programmable DNA binding domain is a modified Streptococcus pyogenes Cas9 (SpCas9), or variants thereof. In various 15 embodiments of the above aspects or any other aspect of the disclosure delineated herein, the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having an altered protospacer-adjacent motif (PAM) specificity or specificity for a non-G PAM. In one embodiment, the modified SpCas9 has specificity for the nucleic acid sequences 5’-NGA-3’. In one embodiment, the modified SpCas9 has specificity for the nucleic acid sequence 5’ 20 AGA-3’ or 5’-GGA-3’. In one embodiment, the modified SpCas9 has specificity for an NGA PAM variant. In various embodiments, the polynucleotide programmable DNA binding domain is a Staphylococcus aureus Cas9 (SaCas9) or variant thereof. In one embodiment, the SaCas9 has specificity for the nucleic acid sequence 5’-NNGRRT-3’. In one embodiment, the 25 SaCas9 has specificity for the nucleic acid sequence 5’-GAGAAT-3’. In one embodiment, the SaCas9 has specificity for an NNGRRT PAM variant. In various embodiments, the polynucleotide programmable DNA binding domain is a Cas12 polypeptide. In one embodiment, the adenosine deaminase variant is inserted in a Cas12 polypeptide. In one embodiment, the Cas12 polypeptide is Cas12a, Cas12b, Cas12c, 30 Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i. In one embodiment, the adenosine deaminase variant is inserted between amino acid positions: a) 153-154, 255-256, 306-307, 980-981, 1019-1020, 534-535, 604-605, or 344-345 of BhCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i; b) 147 and 148, 248 2020221355   24 Feb 2026 and 249, 299 and 300, 991 and 992, or 1031 and 1032 of BvCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i; or c) 157 and 158, 258 and 259, 310 and 311, 1008 and 1009, or 1044 and 1045 of AaCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or 5 Cas12i. In one embodiment, the adenosine deaminase variant is inserted within the Cas12 polypeptide at the loci identified in Table 10B. In one embodiment, the Cas12 polypeptide is Cas12b. In one embodiment, the Cas12 polypeptide comprises a BhCas12b domain, a BvCas12b domain, or an AACas12b domain. In various embodiments the polynucleotide programmable DNA binding domain is 10 a nuclease inactive variant. In other embodiments, the polynucleotide programmable DNA binding domain is a nickase variant. In one embodiment, the nickase variant comprises an amino acid substitution D10A or a corresponding amino acid substitution thereof. In some embodiments, the adenosine deaminase domain is capable of deaminating adenosine in deoxyribonucleic acid (DNA). In some embodiments, the adenosine deaminase domain is a 15 monomer comprising an adenosine deaminase variant. In some embodiments, the adenosine deaminase domain is a heterodimer comprising a wild-type adenosine deaminase domain and an adenosine deaminase variant. In some embodiments, the adenosine deaminase variant comprises the amino acid sequence: 20 MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD; wherein the amino acid sequence comprises at least one alteration. In some embodiments, the adenosine deaminase variant comprises alterations at amino acid position 82 and / or 166, relative to the sequence 25 above. In some embodiments, the at least one alteration comprises: V82S, Y147T, Y147R, Q154S, Y123H, and / or Q154R, relative to the sequence above. In some embodiments, the at least one alteration comprises a combination of alterations selected from the group consisting of: Y147T + Q154R; Y147T + Q154S; Y147R + Q154S; V82S + Q154S; V82S + Y147R; V82S + Q154R; V82S + Y123H; I76Y + V82S; V82S + Y123H + Y147T; V82S + Y123H + 30  Y147R; V82S + Y123H + Q154R; Y147R + Q154R +Y123H; Y147R + Q154R + I76Y; Y147R + Q154R + T166R; Y123H + Y147R + Q154R + I76Y; V82S + Y123H + Y147R + Q154R; and I76Y + V82S + Y123H + Y147R + Q154R. In some embodiments, the at least one alteration is Y147T + Q154S, relative to the sequence above. 2020221355   24 Feb 2026 In some embodiments, the adenosine deaminase variant comprises a deletion of the C terminus beginning at a residue selected from the group consisting of 149, 150, 151, 152, 153, 154, 155, 156, and 157. In some embodiments, the adenosine deaminase variant is an adenosine deaminase monomer comprising a TadA*8 adenosine deaminase variant domain. 5 In some embodiments, the adenosine deaminase variant is an adenosine deaminase heterodimer comprising a wild-type adenosine deaminase domain and a TadA*8 adenosine deaminase variant domain. In some embodiments, the adenosine deaminase variant is an adenosine deaminase heterodimer comprising a TadA domain and a TadA*8 adenosine deaminase variant domain. 10            In some embodiments, the guide polynucleotide comprises a nucleic acid sequence selected from the group of: a) GACCUAGGCGAGGCAGUAGG; b) CCAGUAUGGACACUGUCCAAA; c) CAGUAUGGACACUGUCCAAA; and 15 d) AGUAUGGACACUGUCCAAAG. In some embodiments, the one or more guide RNAs comprises a CRISPR RNA (crRNA) and a trans-encoded small RNA (tracrRNA), wherein the crRNA comprises a nucleic acid sequence complementary to a G6PC nucleic acid sequence comprising the SNP associated with GSD1a. In some embodiments, the Adenosine Deaminase Base Editor 8 (ABE8) is in 20 complex with a single guide RNA (sgRNA) comprising a nucleic acid sequence complementary to an G6PC nucleic acid sequence comprising the SNP associated with GSD1a. In some embodiments, the adenosine deaminase is a TadA deaminase. In one embodiment, the TadA deaminase is a TadA*8 variant. In some embodiments, the TadA*8 25 variant is selected from the group consisting of: TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.4, TadA*8.5, TadA*8.6, TadA*8.7, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, TadA*8.24. In some embodiments, the Adenosine Deaminase Base Editor 8 (ABE8) is selected from the group consisting of: 30   ABE8.1-m, ABE8.2-m, ABE8.3-m, ABE8.4-m, ABE8.5-m, ABE8.6-m, ABE8.7-m, ABE8.8-m, ABE8.9-m, ABE8.10-m, ABE8.11-m, ABE8.12-m, ABE8.13-m, ABE8.14-m, ABE8.15-m, ABE8.16-m, ABE8.17-m, ABE8.18-m, ABE8.19-m, ABE8.20-m, ABE8.21-m, ABE8.22-m, ABE8.23-m, ABE8.24-m, ABE8.1-d, ABE8.2-d, ABE8.3-d, ABE8.4-d, 2020221355   24 Feb 2026 ABE8.5-d, ABE8.6-d, ABE8.7-d, ABE8.8-d, ABE8.9-d, ABE8.10-d, ABE8.11-d, ABE8.12-d, ABE8.13-d, ABE8.14-d, ABE8.15-d, ABE8.16-d, ABE8.17-d, ABE8.18-d, ABE8.19-d, ABE8.20-d, ABE8.21-d, ABE8.22-d, ABE8.23-d, or ABE8.24-d. In some embodiments, the Adenosine Deaminase Base Editor 8 (ABE8) comprises 5 or consists essentially of the following sequence or a fragment thereof having adenosine deaminase activity: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRQVFNAQKKAQSSTD. 10            In some embodiments, the gRNA comprises a scaffold having the following sequence: GUUUUAGAGCUAGAAAUAGCAAGUUAAAAUAAGGCUAGUCCGUUAUCAACUUGAAAAAGUGG CACCGAGUCGGUGCUUUU. In some embodiments, the gRNA comprises a scaffold having the following 15 sequence: GUUUUAGUACUCUGUAAUGAAAAUUACAGAAUCUACUAAAACAAGGCAAAAUGCCGUGUUUA UCUCGUCAACUUGUUGGCGAGAUUUU. In an aspect, provided herein is a base editor comprising an Adenosine Deaminase Base Editor 8 (ABE8) in a complex with one or more guide polynucleotides, wherein the 20 Adenosine Deaminase Base Editor 8 (ABE8) comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, and wherein one or more of said guide polynucleotides target said base editor to effect an A»T to G^C alteration of the SNP associated with GSD1a. In some embodiments, the adenosine deaminase variant comprises a V82S alteration and / or a T166R alteration. In some embodiments, the adenosine deaminase 25 variant further comprises one or more of the following alterations: Y147T, Y147R, Q154S, Y123H, and Q154R. In some embodiments, the base editor domain comprises an adenosine deaminase heterodimer comprising a wild-type adenosine deaminase domain and an adenosine deaminase variant. In some embodiments, the adenosine deaminase variant is a truncated TadA8 that is missing 1, 2, 3, 4, 5 ,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 30   20 N-terminal amino acid residues relative to the full length TadA8. In some embodiments, the adenosine deaminase variant is a truncated TadA8 that is missing 1, 2, 3, 4, 5 ,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 C-terminal amino acid residues relative to the full length TadA8. In some embodiments, the polynucleotide programmable DNA binding 2020221355   24 Feb 2026 domain is a modified Staphylococcus aureus Cas9 (SaCas9), Streptococcus thermophilus 1 Cas9 (St1Cas9), a modified Streptococcus pyogenes Cas9 (SpCas9), or variants thereof. In some embodiments, the polynucleotide programmable DNA binding domain is a variant of SpCas9 having an altered protospacer-adjacent motif (PAM) specificity or specificity for a 5 non-G PAM. In some embodiments, the polynucleotide programmable DNA binding domain is a nuclease inactive Cas9. In some embodiments, the polynucleotide programmable DNA binding domain is a Cas9 nickase. In one aspect, provided herein is a base editor system comprising one or more guide RNAs and a fusion protein comprising a polynucleotide programmable DNA binding domain 10 comprising the following sequence: EIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRK VLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFMQPTVAY SVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLP KYSLFELENGRKRMLASAKFLQKGNELALPSKYVNFLYLASHYEKLKGSPEDNEQK 15 QLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFT LTNLGAPRAFKYFDTTIARKEYRSTKEVLDATLIHQSITGLYETRIDLSQLGGDGGSG GSGGSGGSGGSGGSGGMDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDR HSIKKNLIGALLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFF HRLEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYL 20 ALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSA RLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSNFDLAEDAKLQLSKDTYD DDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTEITKAPLSASMIKRYDEHHQ DLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEE LLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRI 25 PYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPN EKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVT VKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDI VLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQS GKTILDFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAI 30 KKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIK ELGSQILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSF LKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLT KAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNTKYDENDKLIREVKVITL 2020221355   24 Feb 2026 KSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYK VYDVRKMIAKSEQEGADKRTADGSEFESPKKKRKV*, wherein the bold sequence indicates sequence derived from Cas9, the italics sequence denotes a linker sequence, and the underlined sequence denotes a bipartite nuclear localization sequence, and at least one base 5 editor domain comprising an adenosine deaminase variant comprising an alteration at amino acid position 82 and / or 166 of MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPT AHAEIMALRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKT GAAGSLMDVLHYPGMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD 10   , and wherein one or more of said guide polynucleotides target said base editor to effect an A»T to G«C alteration of the SNP associated with GSDla. In an aspect, a cell comprising any one of the above delineated base editor systems is provided. In some embodiments, the cell is a human cell or a mammalian cell. In some embodiments, the cell is ex vivo, in vivo, or in vitro. 15          The description and examples herein illustrate embodiments of the present disclosure in detail. It is to be understood that this disclosure is not limited to the particular embodiments described herein and as such can vary. Those of skill in the art will recognize that there are numerous variations and modifications of this disclosure, which are encompassed within its scope. 20          The practice of some embodiments disclosed herein employ, unless otherwise indicated, conventional techniques of immunology, biochemistry, chemistry, molecular biology, microbiology, cell biology, genomics and recombinant DNA, which are within the skill of the art. See for example Sambrook and Green, Molecular Cloning: A Laboratory Manual, 4th Edition (2012); the series Current Protocols in Molecular Biology (F. M. 25 Ausubel, et al. eds.); the series Methods In Enzymology (Academic Press, Inc.), PCR 2: A Practical Approach (M.J. MacPherson, B.D. Hames and G.R. Taylor eds. (1995)), Harlow and Lane, eds. (1988) Antibodies, A Laboratory Manual, and Culture of Animal Cells: A Manual of Basic Technique and Specialized Applications, 6th Edition (R.I. Freshney, ed. (2010)). 30          Although various features of the present disclosure can be described in the context of a single embodiment, the features can also be provided separately or in any suitable combination. Conversely, although the present disclosure can be described herein in the context of separate embodiments for clarity, the present disclosure can also be implemented 2020221355   24 Feb 2026 in a single embodiment. The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. The features of the present disclosure are set forth with particularity herein. A better understanding of the features and advantages of the disclosure will be obtained by reference 5 to the following detailed description that sets forth illustrative embodiments, in which the principles of the disclosure are utilized, and in view of the accompanying drawings as described hereinbelow. Definitions 10            The following definitions supplement those in the art and are directed to the current application and are not to be imputed to any related or unrelated case, e.g., to any commonly owned patent or application. Although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the present disclosure, the preferred materials and methods are described herein. Accordingly, the terminology used 15 herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms as used herein have the meaning commonly understood by a person skilled in the art to which this disclosure belongs. The following references provide one of skill with a general definition of many of the terms 20 used in this disclosure: Singleton et al., Dictionary of Microbiology and Molecular Biology (2nd ed. 1994); The Cambridge Dictionary of Science and Technology (Walker ed., 1988); The Glossary of Genetics, 5th Ed., R. Rieger et al. (eds.), Springer Verlag (1991); and Hale & Marham, The Harper Collins Dictionary of Biology (1991). In this application, the use of the singular includes the plural unless specifically 25 stated otherwise. It must be noted that, as used in the specification, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. In this application, the use of “or” means “and / or,” unless stated otherwise, and is understood to be inclusive. Furthermore, use of the term “including” as well as other forms, such as “include,” “includes,” and “included,” is not limiting. 30           As used herein, the terms “comprises” and “comprising” are to be construed as being inclusive and open ended rather than exclusive. Specifically, when used in this specification, including the claims, the terms “comprises” and “comprising” and variations thereof mean that the specified elements, features, steps, or components are included. The 2020221355   24 Feb 2026 terms are not to be interpreted to exclude the presence of other elements, features, steps, or components. As used in this specification and claim(s), the words “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as 5 “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited components, elements, features, or method steps. It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method or composition of the present disclosure, and vice versa. Furthermore, compositions of the present disclosure 10 can be used to achieve methods of the present disclosure. The term “about” or “approximately” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, “about” can mean within 1 or more than 1 standard deviation, per the practice 15 in the art. Alternatively, “about” can mean a range of up to 20%, up to 10%, up to 5%, or up to 1% of a given value. Alternatively, particularly with respect to biological systems or processes, the term can mean within an order of magnitude, such as within 5-fold or within 2fold, of a value. Where particular values are described in the application and claims, unless otherwise stated the term “about” meaning within an acceptable error range for the particular 20 value should be assumed. Ranges provided herein are understood to be shorthand for all of the values within the range. For example, a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range from the group consisting 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 25   40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50. Reference in the specification to “some embodiments,” “an embodiment,” “one embodiment” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the present disclosures. 30           By “adenosine deaminase” is meant a polypeptide or fragment thereof capable of catalyzing the hydrolytic deamination of adenine or adenosine. In some embodiments, the deaminase or deaminase domain is an adenosine deaminase catalyzing the hydrolytic deamination of adenosine to inosine or deoxy adenosine to deoxyinosine. In some 2020221355   24 Feb 2026 embodiments, the adenosine deaminase catalyzes the hydrolytic deamination of adenine or adenosine in deoxyribonucleic acid (DNA). The adenosine deaminases (e.g., engineered adenosine deaminases, evolved adenosine deaminases) provided herein may be from any organism, such as a bacterium. 5         In some embodiments, the adenosine deaminase is a TadA deaminase. In some embodiments, the TadA deaminase is TadA variant. In some embodiments, the TadA variant is a TadA*8. In some embodiments, the deaminase or deaminase domain is a variant of a naturally occurring deaminase from an organism, such as a human, chimpanzee, gorilla, monkey, cow, dog, rat, or mouse. In some embodiments, the deaminase or deaminase domain 10 does not occur in nature. For example, in some embodiments, the deaminase or deaminase domain is 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 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%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or 15 at least 99.9% identical to a naturally occurring deaminase. For example, deaminase domains are described in International PCT Application Nos. PCT / 2017 / 045381 (WO 2018 / 027078) and PCT / US2016 / 058344 (WO 2017 / 070632), each of which is incorporated herein by reference for its entirety. Also, see Komor, A.C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); 20 Gaudelli, N.M., et al., “Programmable base editing of A»T to G*C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); Komor, A.C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017) ), and Rees, H.A., et al., “Base editing: precision chemistry on the genome and transcriptome of living cells.” Nat 25 Rev Genet. 2018 Dec;19(12):770-788. doi: 10.1038 / s41576-018-0059-1, the entire contents of which are hereby incorporated by reference. A wild type TadA(wt) adenosine deaminase has the following sequence (also termed TadA reference sequence): MSEVEFSHEYWMRHALTLAKRAWDEREVPVGAVLVHNNRVIGEGWNRPIGRHDPTAHAEIMA 30 LRQGGLVMQNYRLIDATLYVTLEPCVMCAGAMIHSRIGRVVFGARDAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLSDFFRMRRQEIKAQKKAQSSTD In some embodiments, the adenosine deaminase comprises an alteration in the following sequence: 2020221355   24 Feb 2026 MSEVEFSHEY WMRHALTLAK RARDEREVPV GAVLVLNNRV IGEGWNRAIG LHDPTAHAEI MALRQGGLVM QNYRLIDATL YVTFEPCVMC AGAMIHSRIG RVVFGVRNAK TGAAGSLMDV LHYPGMNHRV EITEGILADE CAALLCYFFR MPRQVFNAQK KAQSSTD 5 (also termed TadA*7.10). In some embodiments, TadA*7.10 comprises at least one alteration. In some embodiments, TadA*7.10 comprises an alteration at amino acid 82 and / or 166. In particular embodiments, a variant of the above-referenced sequence comprises one or more of the following alterations: Y147T, Y147R, Q154S, Y123H, V82S, T166R, and / or Q154R. The 10 alteration Y123H is also referred to herein as H123H (the alteration H123Y in TadA*7.10 reverted back to Y123H (wt)). In other embodiments, a variant of the TadA*7.10 sequence comprises a combination of alterations selected from the group of: Y147T + Q154R; Y147T + Q154S; Y147R + Q154S; V82S + Q154S; V82S + Y147R; V82S + Q154R; V82S + Y123H; I76Y + V82S; V82S + Y123H + Y147T; V82S + Y123H + Y147R; V82S + Y123H 15  + Q154R; Y147R + Q154R +Y123H; Y147R + Q154R + I76Y; Y147R + Q154R + T166R; Y123H + Y147R + Q154R + I76Y; V82S + Y123H + Y147R + Q154R; and I76Y + V82S + Y123H + Y147R + Q154R. In other embodiments, the disclosure provides adenosine deaminase variants that include deletions, e.g., TadA*8, comprising a deletion of the C terminus beginning at residue 20   149, 150, 151, 152, 153, 154, 155, 156, or 157, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the adenosine deaminase variant is a TadA (e.g., TadA*8) monomer comprising one or more of the following alterations: Y147T, Y147R, Q154S, Y123H, V82S, T166R, and / or Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another 25 TadA. In other embodiments, the adenosine deaminase variant is a monomer comprising a combination of alterations selected from the group of: Y147T + Q154R; Y147T + Q154S; Y147R + Q154S; V82S + Q154S; V82S + Y147R; V82S + Q154R; V82S + Y123H; I76Y + V82S; V82S + Y123H + Y147T; V82S + Y123H + Y147R; V82S + Y123H + Q154R; Y147R + Q154R +Y123H; Y147R + Q154R + I76Y; Y147R + Q154R + T166R; Y123H + 30  Y147R + Q154R + I76Y; V82S + Y123H + Y147R + Q154R; and I76Y + V82S + Y123H + Y147R + Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. 2020221355   24 Feb 2026 In still other embodiments, the adenosine deaminase variant is a homodimer comprising two adenosine deaminase domains (e.g., TadA*8) each having one or more of the following alterations Y147T, Y147R, Q154S, Y123H, V82S, T166R, and / or Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. 5 In other embodiments, the adenosine deaminase variant is a homodimer comprising two adenosine deaminase domains (e.g., TadA*8) each having a combination of alterations selected from the group of: Y147T + Q154R; Y147T + Q154S; Y147R + Q154S; V82S + Q154S; V82S + Y147R; V82S + Q154R; V82S + Y123H; I76Y + V82S; V82S + Y123H + Y147T; V82S + Y123H + Y147R; V82S + Y123H + Q154R; Y147R + Q154R +Y123H; 10  Y147R + Q154R + I76Y; Y147R + Q154R + T166R; Y123H + Y147R + Q154R + I76Y; V82S + Y123H + Y147R + Q154R; and I76Y + V82S + Y123H + Y147R + Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the adenosine deaminase variant is a heterodimer comprising a wild-type TadA adenosine deaminase domain and an adenosine deaminase variant domain 15   (e.g., TadA*8) comprising one or more of the following alterations Y147T, Y147R, Q154S, Y123H, V82S, T166R, and / or Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the adenosine deaminase variant is a heterodimer comprising a wild-type TadA adenosine deaminase domain and an adenosine deaminase variant domain (e.g. TadA*8) comprising a combination 20 of alterations selected from the group of: Y147T + Q154R; Y147T + Q154S; Y147R + Q154S; V82S + Q154S; V82S + Y147R; V82S + Q154R; V82S + Y123H; I76Y + V82S; V82S + Y123H + Y147T; V82S + Y123H + Y147R; V82S + Y123H + Q154R; Y147R + Q154R +Y123H; Y147R + Q154R + I76Y; Y147R + Q154R + T166R; Y123H + Y147R + Q154R + I76Y; V82S + Y123H + Y147R + Q154R; and I76Y + V82S + Y123H + Y147R + 25   Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the adenosine deaminase variant is a heterodimer comprising a TadA*7.10 domain and an adenosine deaminase variant domain (e.g., TadA*8) comprising one or more of the following alterations Y147T, Y147R, Q154S, Y123H, V82S, T166R, 30 and / or Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the adenosine deaminase variant is a heterodimer comprising a TadA*7.10 domain and an adenosine deaminase variant domain (e.g. TadA*8) comprising a combination of the following alterations: Y147T + Q154R; 2020221355   24 Feb 2026 Y147T + Q154S; Y147R + Q154S; V82S + Q154S; V82S + Y147R; V82S + Q154R; V82S + Y123H; I76Y + V82S; V82S + Y123H + Y147T; V82S + Y123H + Y147R; V82S + Y123H + Q154R; Y147R + Q154R +Y123H; Y147R + Q154R + I76Y; Y147R + Q154R + T166R; Y123H + Y147R + Q154R + I76Y; V82S + Y123H + Y147R + Q154R; or I76Y + 5 V82S + Y123H + Y147R + Q154R, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In one embodiment, the adenosine deaminase is a TadA*8 that comprises or consists essentially of the following sequence or a fragment thereof having adenosine deaminase activity: 10 MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRQVFNAQKKAQSSTD. In some embodiments, the TadA*8 is truncated. In some embodiments, the truncated TadA*8 is missing 1, 2, 3, 4, 5 ,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 N- 15 terminal amino acid residues relative to the full length TadA*8. In some embodiments, the truncated TadA*8 is missing 1, 2, 3, 4, 5 ,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 C-terminal amino acid residues relative to the full length TadA*8. In some embodiments the adenosine deaminase variant is a full-length TadA*8. In particular embodiments, an adenosine deaminase heterodimer comprises a TadA*8 20 domain and an adenosine deaminase domain selected from one of the following: Staphylococcus aureus (S. aureus) TadA: MGSHMTNDIYFMTLAIEEAKKAAQLGEVPIGAIITKDDEVIARAHNLRETLQQPTAHAEHIA IERAAKVLGSWRLEGCTLYVTLEPCVMCAGTIVMSRIPRVVYGADDPKGGCSGSLMNLLQQS NFNHRAIVDKGVLKEACSTLLTTFFKNLRANKKSTN 25   Bacillus subtilis (B. subtilis) TadA: MTQDELYMKEAIKEAKKAEEKGEVPIGAVLVINGEIIARAHNLRETEQRSIAHAEMLVIDEA CKALGTWRLEGATLYVTLEPCPMCAGAVVLSRVEKVVFGAFDPKGGCSGTLMNLLQEERFNH QAEVVSGVLEEECGGMLSAFFRELRKKKKAARKNLSE Salmonella typhimurium (S. typhimurium) TadA: 30 MPPAFITGVTSLSDVELDHEYWMRHALTLAKRAWDEREVPVGAVLVHNHRVIGEGWNRPIGR HDPTAHAEIMALRQGGLVLQNYRLLDTTLYVTLEPCVMCAGAMVHSRIGRVVFGARDAKTGA AGSLIDVLHHPGMNHRVEIIEGVLRDECATLLSDFFRMRRQEIKALKKADRAEGAGPAV Shewanella putrefaciens (S. putrefaciens) TadA: 2020221355   24 Feb 2026 MDEYWMQVAMQMAEKAEAAGEVPVGAVLVKDGQQIATGYNLSISQHDPTAHAEILCLRSAGK KLENYRLLDATLYITLEPCAMCAGAMVHSRIARVVYGARDEKTGAAGTVVNLLQHPAFNHQV EVTSGVLAEACSAQLSRFFKRRRDEKKALKLAQRAQQGIE Haemophilus influenzae F3031 (H. influenzae) TadA: 5 MDAAKVRSEFDEKMMRYALELADKAEALGEIPVGAVLVDDARNIIGEGWNLSIVQSDPTAHA EIIALRNGAKNIQNYRLLNSTLYVTLEPCTMCAGAILHSRIKRLVFGASDYKTGAIGSRFHF FDDYKMNHTLEITSGVLAEECSQKLSTFFQKRREEKKIEKALLKSLSDK Caulobacter crescentus (C. crescentus) TadA: MRTDESEDQDHRMMRLALDAARAAAEAGETPVGAVILDPSTGEVIATAGNGPIAAHDPTAHA 10 EIAAMRAAAAKLGNYRLTDLTLVVTLEPCAMCAGAISHARIGRVVFGADDPKGGAVVHGPKF FAQPTCHWRPEVTGGVLADESADLLRGFFRARRKAKI Geobacter sulfurreducens (G. sulfurreducens) TadA: MSSLKKTPIRDDAYWMGKAIREAAKAAARDEVPIGAVIVRDGAVIGRGHNLREGSNDPSAHA EMIAIRQAARRSANWRLTGATLYVTLEPCLMCMGAIILARLERVVFGCYDPKGGAAGSLYDL 15 SADPRLNHQVRLSPGVCQEECGTMLSDFFRDLRRRKKAKATPALFIDERKVPPEP TadA*7.10 MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD 20         By “Adenosine Deaminase Base Editor 8 (ABE8) polypeptide” or “ABE8” is meant a base editor as defined herein comprising an adenosine deaminase variant comprising an alteration at amino acid position 82 and / or 166 of the following reference sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPT AHAEIMALRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKT 25 GAAGSLMDVLHYPGMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD In some embodiments, ABE8 comprises further alterations, as described herein, relative to the reference sequence. By “Adenosine Deaminase Base Editor 8 (ABE8) polynucleotide” is meant a polynucleotide encoding an ABE8. 30          “Administering” is referred to herein as providing one or more compositions described herein to a patient or a subject. By way of example and without limitation, composition administration, e.g., injection, can be performed by intravenous (i.v.) injection, sub-cutaneous (s.c.) injection, intradermal (i.d.) injection, intraperitoneal (i.p.) injection, or intramuscular (i.m.) injection. One or more such routes can be employed. Parenteral 2020221355   24 Feb 2026 administration can be, for example, by bolus injection or by gradual perfusion over time. Alternatively, or concurrently, administration can be by the oral route. By “agent” is meant any small molecule chemical compound, antibody, nucleic acid molecule, or polypeptide, or fragments thereof. 5           By “alteration” is meant a change (e.g. increase or decrease) in the structure, expression levels or activity of a gene or polypeptide as detected by standard art known methods such as those described herein. As used herein, an alteration includes a change in a polynucleotide or polypeptide sequence or a change in expression levels, such as a 25% change, a 40% change, a 50% change, or greater. 10           By “ameliorate” is meant decrease, suppress, attenuate, diminish, arrest, or stabilize the development or progression of a disease. By “analog” is meant a molecule that is not identical, but has analogous functional or structural features. For example, a polynucleotide or polypeptide analog retains the biological activity of a corresponding naturally-occurring polynucleotide or polypeptide, 15 while having certain modifications that enhance the analog's function relative to a naturally occurring polynucleotide or polypeptide. Such modifications could increase the analog's affinity for DNA, efficiency, specificity, protease or nuclease resistance, membrane permeability, and / or half-life, without altering, for example, ligand binding. An analog may include an unnatural nucleotide or amino acid. 20            By "base editor (BE)" or "nucleobase editor (NBE)" is meant an agent that binds a polynucleotide and has nucleobase modifying activity. In various embodiment, the base editor comprises a nucleobase modifying polypeptide (e.g., a deaminase) and a nucleic acid programmable nucleotide binding domain in conjunction with a guide polynucleotide (e.g., guide RNA). In various embodiments, the agent is a biomolecular complex comprising a 25 protein domain having base editing activity, i.e., a domain capable of modifying a base (e.g., A, T, C, G, or U) within a nucleic acid molecule (e.g., DNA). In some embodiments, the polynucleotide programmable DNA binding domain is fused or linked to a deaminase domain. In one embodiment, the agent is a fusion protein comprising a domain having base editing activity. In another embodiment, the protein domain having base editing activity is 30 linked to the guide RNA (e.g., via an RNA binding motif on the guide RNA and an RNA binding domain fused to the deaminase). In some embodiments, the domain having base editing activity is capable of deaminating a base within a nucleic acid molecule. In some embodiments, the base editor is capable of deaminating one or more bases within a DNA 2020221355   24 Feb 2026 molecule. In some embodiments, the base editor is capable of deaminating an adenosine (A) within DNA. In some embodiments, the base editor is an adenosine base editor (ABE). In some embodiments, base editors are generated (e.g. ABE8) by cloning an adenosine deaminase variant (e.g., TadA*8) into a scaffold that includes a circular permutant 5   Cas9 (e.g., spCAS9 or saCAS9) and a bipartite nuclear localization sequence. Circular permutant Cas9s are known in the art and described, for example, in Oakes et al., Cell 176, 254-267, 2019. Exemplary circular permutants follow where the bold sequence indicates sequence derived from Cas9, the italics sequence denotes a linker sequence, and the underlined sequence denotes a bipartite nuclear localization sequence. 10 CP5 (with MSP “NGC=Pam Variant with mutations Regular Cas9 likes NGG” PID=Protein Interacting Domain and “D10A” nickase): EIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSM PQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFMQPTVAYSVLVVAKVEK GKSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRM 15 LASAKFLQKGNELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISE FSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPRAFKYFDTTIARKEYR STKEVLDATLIHQSITGLYETRIDLSQLGGDGGSGGSGGSGGSGGSGGSGGMDKKYSIGLAI GTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATRLKRTARRRYT RRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTI 20 YHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFE ENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSNFDLA EDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTEITKAPLSASM IKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKM DGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILT 25 FRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKV LPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTVKQLKEDYF KKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREM IEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRNF MQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHK 30 PENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYLQ NGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKM KNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNT 2020221355   24 Feb 2026 KYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKKYPK LESEFVYGDYKVYDVRKMIAKSEQEGADKRTADGSEFESPKKKRKV* In some embodiments, the ABE8 is selected from a base editor from Table 7 or 9 infra. In some embodiments, ABE8 contains an adenosine deaminase variant evolved from 5 TadA. In some embodiments, the adenosine deaminase variant of ABE8 is a TadA*8 variant as described in Table 7 or 9 infra. In some embodiments, the adenosine deaminase variant is TadA*7.10 variant (e.g. TadA*8) comprising one or more of an alteration selected from the group of Y147T, Y147R, Q154S, Y123H, V82S, T166R, and / or Q154R. In various embodiments, ABE8 comprises TadA*7.10 variant (e.g. TadA*8) with a combination of 10 alterations selected from the group of Y147T + Q154R; Y147T + Q154S; Y147R + Q154S; V82S + Q154S; V82S + Y147R; V82S + Q154R; V82S + Y123H; I76Y + V82S; V82S + Y123H + Y147T; V82S + Y123H + Y147R; V82S + Y123H + Q154R; Y147R + Q154R +Y123H; Y147R + Q154R + I76Y; Y147R + Q154R + T166R; Y123H + Y147R + Q154R + I76Y; V82S + Y123H + Y147R + Q154R; and I76Y + V82S + Y123H + Y147R + Q154R. 15 In some embodiments ABE8 is a monomeric construct. In some embodiments, ABE8 is a heterodimeric construct. In some embodiments, the Adenosine Deaminase Base Editor 8 (ABE8) comprises the sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP 20 GMNHRVEITEGILADECAALLCTFFRMPRQVFNAQKKAQSSTD. In some embodiments, the polynucleotide programmable DNA binding domain is a CRISPR associated (e.g., Cas or Cpf1) enzyme. In some embodiments, the base editor is a catalytically dead Cas9 (dCas9) fused to a deaminase domain. In some embodiments, the base editor is a Cas9 nickase (nCas9) fused to a deaminase domain. Details of base editors 25 are described in International PCT Application Nos. PCT / 2017 / 045381 (WO 2018 / 027078) and PCT / US2016 / 058344 (WO 2017 / 070632), each of which is incorporated herein by reference for its entirety. Also see Komor, A.C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N.M., et al., “Programmable base editing of A»T to G•C in genomic DNA without 30 DNA cleavage” Nature 551, 464-471 (2017); Komor, A.C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), and Rees, H.A., et al., “Base editing: precision chemistry on the genome and transcriptome of living cells.” 2020221355   24 Feb 2026 Nat Rev Genet. 2018 Dec;19(12):770-788. doi: 10.1038 / s41576-018-0059-1, the entire contents of which are hereby incorporated by reference. By way of example, the adenine base editor (ABE) as used in the base editing compositions, systems and methods described herein has the nucleic acid sequence (8877 5 base pairs), (Addgene, Watertown, MA.; Gaudelli NM, et al., Nature. 2017 Nov 23;551(7681):464-471. doi: 10.1038 / nature24644; Koblan LW, et al., Nat Biotechnol. 2018 Oct;36(9):843-846. doi: 10.1038 / nbt.4172.) as provided below. Polynucleotide sequences having at least 95% or greater identity to the ABE nucleic acid sequence are also encompassed. 10 ATATGCCAAGTACGCCCCCTATTGACGTCAATGACGGTAAATGGCCCGCCTGGCATTATGCCCAGTACAT GACCTTATGGGACTTTCCTACTTGGCAGTACATCTACGTATTAGTCATCGCTATTACCATGGTGATGCGG TTTTGGCAGTACATCAATGGGCGTGGATAGCGGTTTGACTCACGGGGATTTCCAAGTCTCCACCCCATTG ACGTCAATGGGAGTTTGTTTTGGCACCAAAATCAACGGGACTTTCCAAAATGTCGTAACAACTCCGCCCC ATTGACGCAAATGGGCGGTAGGCGTGTACGGTGGGAGGTCTATATAAGCAGAGCTGGTTTAGTGAACCGT 15 CAGATCCGCTAGAGATCCGCGGCCGCTAATACGACTCACTATAGGGAGAGCCGCCACCATGAAACGGACA GCCGACGGAAGCGAGTTCGAGTCACCAAAGAAGAAGCGGAAAGTCTCTGAAGTCGAGTTTAGCCACGAGT ATTGGATGAGGCACGCACTGACCCTGGCAAAGCGAGCATGGGATGAAAGAGAAGTCCCCGTGGGCGCCGT GCTGGTGCACAACAATAGAGTGATCGGAGAGGGATGGAACAGGCCAATCGGCCGCCACGACCCTACCGCA CACGCAGAGATCATGGCACTGAGGCAGGGAGGCCTGGTCATGCAGAATTACCGCCTGATCGATGCCACCC 20 TGTATGTGACACTGGAGCCATGCGTGATGTGCGCAGGAGCAATGATCCACAGCAGGATCGGAAGAGTGGT GTTCGGAGCACGGGACGCCAAGACCGGCGCAGCAGGCTCCCTGATGGATGTGCTGCACCACCCCGGCATG AACCACCGGGTGGAGATCACAGAGGGAATCCTGGCAGACGAGTGCGCCGCCCTGCTGAGCGATTTCTTTA GAATGCGGAGACAGGAGATCAAGGCCCAGAAGAAGGCACAGAGCTCCACCGACTCTGGAGGATCTAGCGG AGGATCCTCTGGAAGCGAGACACCAGGCACAAGCGAGTCCGCCACACCAGAGAGCTCCGGCGGCTCCTCC 25 GGAGGATCCTCTGAGGTGGAGTTTTCCCACGAGTACTGGATGAGACATGCCCTGACCCTGGCCAAGAGGG CACGCGATGAGAGGGAGGTGCCTGTGGGAGCCGTGCTGGTGCTGAACAATAGAGTGATCGGCGAGGGCTG GAACAGAGCCATCGGCCTGCACGACCCAACAGCCCATGCCGAAATTATGGCCCTGAGACAGGGCGGCCTG GTCATGCAGAACTACAGACTGATTGACGCCACCCTGTACGTGACATTCGAGCCTTGCGTGATGTGCGCCG GCGCCATGATCCACTCTAGGATCGGCCGCGTGGTGTTTGGCGTGAGGAACGCAAAAACCGGCGCCGCAGG 30 CTCCCTGATGGACGTGCTGCACTACCCCGGCATGAATCACCGCGTCGAAATTACCGAGGGAATCCTGGCA GATGAATGTGCCGCCCTGCTGTGCTATTTCTTTCGGATGCCTAGACAGGTGTTCAATGCTCAGAAGAAGG CCCAGAGCTCCACCGACTCCGGAGGATCTAGCGGAGGCTCCTCTGGCTCTGAGACACCTGGCACAAGCGA GAGCGCAACACCTGAAAGCAGCGGGGGCAGCAGCGGGGGGTCAGACAAGAAGTACAGCATCGGCCTGGCC ATCGGCACCAACTCTGTGGGCTGGGCCGTGATCACCGACGAGTACAAGGTGCCCAGCAAGAAATTCAAGG 35 TGCTGGGCAACACCGACCGGCACAGCATCAAGAAGAACCTGATCGGAGCCCTGCTGTTCGACAGCGGCGA AACAGCCGAGGCCACCCGGCTGAAGAGAACCGCCAGAAGAAGATACACCAGACGGAAGAACCGGATCTGC TATCTGCAAGAGATCTTCAGCAACGAGATGGCCAAGGTGGACGACAGCTTCTTCCACAGACTGGAAGAGT CCTTCCTGGTGGAAGAGGATAAGAAGCACGAGCGGCACCCCATCTTCGGCAACATCGTGGACGAGGTGGC 2020221355   24 Feb 2026 CTACCACGAGAAGTACCCCACCATCTACCACCTGAGAAAGAAACTGGTGGACAGCACCGACAAGGCCGAC CTGCGGCTGATCTATCTGGCCCTGGCCCACATGATCAAGTTCCGGGGCCACTTCCTGATCGAGGGCGACC TGAACCCCGACAACAGCGACGTGGACAAGCTGTTCATCCAGCTGGTGCAGACCTACAACCAGCTGTTCGA GGAAAACCCCATCAACGCCAGCGGCGTGGACGCCAAGGCCATCCTGTCTGCCAGACTGAGCAAGAGCAGA 5 CGGCTGGAAAATCTGATCGCCCAGCTGCCCGGCGAGAAGAAGAATGGCCTGTTCGGAAACCTGATTGCCC TGAGCCTGGGCCTGACCCCCAACTTCAAGAGCAACTTCGACCTGGCCGAGGATGCCAAACTGCAGCTGAG CAAGGACACCTACGACGACGACCTGGACAACCTGCTGGCCCAGATCGGCGACCAGTACGCCGACCTGTTT CTGGCCGCCAAGAACCTGTCCGACGCCATCCTGCTGAGCGACATCCTGAGAGTGAACACCGAGATCACCA AGGCCCCCCTGAGCGCCTCTATGATCAAGAGATACGACGAGCACCACCAGGACCTGACCCTGCTGAAAGC 10 TCTCGTGCGGCAGCAGCTGCCTGAGAAGTACAAAGAGATTTTCTTCGACCAGAGCAAGAACGGCTACGCC GGCTACATTGACGGCGGAGCCAGCCAGGAAGAGTTCTACAAGTTCATCAAGCCCATCCTGGAAAAGATGG ACGGCACCGAGGAACTGCTCGTGAAGCTGAACAGAGAGGACCTGCTGCGGAAGCAGCGGACCTTCGACAA CGGCAGCATCCCCCACCAGATCCACCTGGGAGAGCTGCACGCCATTCTGCGGCGGCAGGAAGATTTTTAC CCATTCCTGAAGGACAACCGGGAAAAGATCGAGAAGATCCTGACCTTCCGCATCCCCTACTACGTGGGCC 15 CTCTGGCCAGGGGAAACAGCAGATTCGCCTGGATGACCAGAAAGAGCGAGGAAACCATCACCCCCTGGAA CTTCGAGGAAGTGGTGGACAAGGGCGCTTCCGCCCAGAGCTTCATCGAGCGGATGACCAACTTCGATAAG AACCTGCCCAACGAGAAGGTGCTGCCCAAGCACAGCCTGCTGTACGAGTACTTCACCGTGTATAACGAGC TGACCAAAGTGAAATACGTGACCGAGGGAATGAGAAAGCCCGCCTTCCTGAGCGGCGAGCAGAAAAAGGC CATCGTGGACCTGCTGTTCAAGACCAACCGGAAAGTGACCGTGAAGCAGCTGAAAGAGGACTACTTCAAG 20 AAAATCGAGTGCTTCGACTCCGTGGAAATCTCCGGCGTGGAAGATCGGTTCAACGCCTCCCTGGGCACAT ACCACGATCTGCTGAAAATTATCAAGGACAAGGACTTCCTGGACAATGAGGAAAACGAGGACATTCTGGA AGATATCGTGCTGACCCTGACACTGTTTGAGGACAGAGAGATGATCGAGGAACGGCTGAAAACCTATGCC CACCTGTTCGACGACAAAGTGATGAAGCAGCTGAAGCGGCGGAGATACACCGGCTGGGGCAGGCTGAGCC GGAAGCTGATCAACGGCATCCGGGACAAGCAGTCCGGCAAGACAATCCTGGATTTCCTGAAGTCCGACGG 25 CTTCGCCAACAGAAACTTCATGCAGCTGATCCACGACGACAGCCTGACCTTTAAAGAGGACATCCAGAAA GCCCAGGTGTCCGGCCAGGGCGATAGCCTGCACGAGCACATTGCCAATCTGGCCGGCAGCCCCGCCATTA AGAAGGGCATCCTGCAGACAGTGAAGGTGGTGGACGAGCTCGTGAAAGTGATGGGCCGGCACAAGCCCGA GAACATCGTGATCGAAATGGCCAGAGAGAACCAGACCACCCAGAAGGGACAGAAGAACAGCCGCGAGAGA ATGAAGCGGATCGAAGAGGGCATCAAAGAGCTGGGCAGCCAGATCCTGAAAGAACACCCCGTGGAAAACA 30 CCCAGCTGCAGAACGAGAAGCTGTACCTGTACTACCTGCAGAATGGGCGGGATATGTACGTGGACCAGGA ACTGGACATCAACCGGCTGTCCGACTACGATGTGGACCATATCGTGCCTCAGAGCTTTCTGAAGGACGAC TCCATCGACAACAAGGTGCTGACCAGAAGCGACAAGAACCGGGGCAAGAGCGACAACGTGCCCTCCGAAG AGGTCGTGAAGAAGATGAAGAACTACTGGCGGCAGCTGCTGAACGCCAAGCTGATTACCCAGAGAAAGTT CGACAATCTGACCAAGGCCGAGAGAGGCGGCCTGAGCGAACTGGATAAGGCCGGCTTCATCAAGAGACAG 35 CTGGTGGAAACCCGGCAGATCACAAAGCACGTGGCACAGATCCTGGACTCCCGGATGAACACTAAGTACG ACGAGAATGACAAGCTGATCCGGGAAGTGAAAGTGATCACCCTGAAGTCCAAGCTGGTGTCCGATTTCCG GAAGGATTTCCAGTTTTACAAAGTGCGCGAGATCAACAACTACCACCACGCCCACGACGCCTACCTGAAC GCCGTCGTGGGAACCGCCCTGATCAAAAAGTACCCTAAGCTGGAAAGCGAGTTCGTGTACGGCGACTACA AGGTGTACGACGTGCGGAAGATGATCGCCAAGAGCGAGCAGGAAATCGGCAAGGCTACCGCCAAGTACTT 40 CTTCTACAGCAACATCATGAACTTTTTCAAGACCGAGATTACCCTGGCCAACGGCGAGATCCGGAAGCGG CCTCTGATCGAGACAAACGGCGAAACCGGGGAGATCGTGTGGGATAAGGGCCGGGATTTTGCCACCGTGC 2020221355   24 Feb 2026 GGAAAGTGCTGAGCATGCCCCAAGTGAATATCGTGAAAAAGACCGAGGTGCAGACAGGCGGCTTCAGCAA AGAGTCTATCCTGCCCAAGAGGAACAGCGATAAGCTGATCGCCAGAAAGAAGGACTGGGACCCTAAGAAG TACGGCGGCTTCGACAGCCCCACCGTGGCCTATTCTGTGCTGGTGGTGGCCAAAGTGGAAAAGGGCAAGT CCAAGAAACTGAAGAGTGTGAAAGAGCTGCTGGGGATCACCATCATGGAAAGAAGCAGCTTCGAGAAGAA 5 TCCCATCGACTTTCTGGAAGCCAAGGGCTACAAAGAAGTGAAAAAGGACCTGATCATCAAGCTGCCTAAG TACTCCCTGTTCGAGCTGGAAAACGGCCGGAAGAGAATGCTGGCCTCTGCCGGCGAACTGCAGAAGGGAA ACGAACTGGCCCTGCCCTCCAAATATGTGAACTTCCTGTACCTGGCCAGCCACTATGAGAAGCTGAAGGG CTCCCCCGAGGATAATGAGCAGAAACAGCTGTTTGTGGAACAGCACAAGCACTACCTGGACGAGATCATC GAGCAGATCAGCGAGTTCTCCAAGAGAGTGATCCTGGCCGACGCTAATCTGGACAAAGTGCTGTCCGCCT 10 ACAACAAGCACCGGGATAAGCCCATCAGAGAGCAGGCCGAGAATATCATCCACCTGTTTACCCTGACCAA TCTGGGAGCCCCTGCCGCCTTCAAGTACTTTGACACCACCATCGACCGGAAGAGGTACACCAGCACCAAA GAGGTGCTGGACGCCACCCTGATCCACCAGAGCATCACCGGCCTGTACGAGACACGGATCGACCTGTCTC AGCTGGGAGGTGACTCTGGCGGCTCAAAAAGAACCGCCGACGGCAGCGAATTCGAGCCCAAGAAGAAGAG GAAAGTCTAACCGGTCATCATCACCATCACCATTGAGTTTAAACCCGCTGATCAGCCTCGACTGTGCCTT 15 CTAGTTGCCAGCCATCTGTTGTTTGCCCCTCCCCCGTGCCTTCCTTGACCCTGGAAGGTGCCACTCCCAC TGTCCTTTCCTAATAAAATGAGGAAATTGCATCGCATTGTCTGAGTAGGTGTCATTCTATTCTGGGGGGT GGGGTGGGGCAGGACAGCAAGGGGGAGGATTGGGAAGACAATAGCAGGCATGCTGGGGATGCGGTGGGCT CTATGGCTTCTGAGGCGGAAAGAACCAGCTGGGGCTCGATACCGTCGACCTCTAGCTAGAGCTTGGCGTA ATCATGGTCATAGCTGTTTCCTGTGTGAAATTGTTATCCGCTCACAATTCCACACAACATACGAGCCGGA 20 AGCATAAAGTGTAAAGCCTAGGGTGCCTAATGAGTGAGCTAACTCACATTAATTGCGTTGCGCTCACTGC CCGCTTTCCAGTCGGGAAACCTGTCGTGCCAGCTGCATTAATGAATCGGCCAACGCGCGGGGAGAGGCGG TTTGCGTATTGGGCGCTCTTCCGCTTCCTCGCTCACTGACTCGCTGCGCTCGGTCGTTCGGCTGCGGCGA GCGGTATCAGCTCACTCAAAGGCGGTAATACGGTTATCCACAGAATCAGGGGATAACGCAGGAAAGAACA TGTGAGCAAAAGGCCAGCAAAAGGCCAGGAACCGTAAAAAGGCCGCGTTGCTGGCGTTTTTCCATAGGCT 25 CCGCCCCCCTGACGAGCATCACAAAAATCGACGCTCAAGTCAGAGGTGGCGAAACCCGACAGGACTATAA AGATACCAGGCGTTTCCCCCTGGAAGCTCCCTCGTGCGCTCTCCTGTTCCGACCCTGCCGCTTACCGGAT ACCTGTCCGCCTTTCTCCCTTCGGGAAGCGTGGCGCTTTCTCATAGCTCACGCTGTAGGTATCTCAGTTC GGTGTAGGTCGTTCGCTCCAAGCTGGGCTGTGTGCACGAACCCCCCGTTCAGCCCGACCGCTGCGCCTTA TCCGGTAACTATCGTCTTGAGTCCAACCCGGTAAGACACGACTTATCGCCACTGGCAGCAGCCACTGGTA 30 ACAGGATTAGCAGAGCGAGGTATGTAGGCGGTGCTACAGAGTTCTTGAAGTGGTGGCCTAACTACGGCTA CACTAGAAGAACAGTATTTGGTATCTGCGCTCTGCTGAAGCCAGTTACCTTCGGAAAAAGAGTTGGTAGC TCTTGATCCGGCAAACAAACCACCGCTGGTAGCGGTGGTTTTTTTGTTTGCAAGCAGCAGATTACGCGCA GAAAAAAAGGATCTCAAGAAGATCCTTTGATCTTTTCTACGGGGTCTGACACTCAGTGGAACGAAAACTC ACGTTAAGGGATTTTGGTCATGAGATTATCAAAAAGGATCTTCACCTAGATCCTTTTAAATTAAAAATGA 35 AGTTTTAAATCAATCTAAAGTATATATGAGTAAACTTGGTCTGACAGTTACCAATGCTTAATCAGTGAGG CACCTATCTCAGCGATCTGTCTATTTCGTTCATCCATAGTTGCCTGACTCCCCGTCGTGTAGATAACTAC GATACGGGAGGGCTTACCATCTGGCCCCAGTGCTGCAATGATACCGCGAGACCCACGCTCACCGGCTCCA GATTTATCAGCAATAAACCAGCCAGCCGGAAGGGCCGAGCGCAGAAGTGGTCCTGCAACTTTATCCGCCT CCATCCAGTCTATTAATTGTTGCCGGGAAGCTAGAGTAAGTAGTTCGCCAGTTAATAGTTTGCGCAACGT 40 TGTTGCCATTGCTACAGGCATCGTGGTGTCACGCTCGTCGTTTGGTATGGCTTCATTCAGCTCCGGTTCC CAACGATCAAGGCGAGTTACATGATCCCCCATGTTGTGCAAAAAAGCGGTTAGCTCCTTCGGTCCTCCGA 2020221355   24 Feb 2026 TCGTTGTCAGAAGTAAGTTGGCCGCAGTGTTATCACTCATGGTTATGGCAGCACTGCATAATTCTCTTAC TGTCATGCCATCCGTAAGATGCTTTTCTGTGACTGGTGAGTACTCAACCAAGTCATTCTGAGAATAGTGT ATGCGGCGACCGAGTTGCTCTTGCCCGGCGTCAATACGGGATAATACCGCGCCACATAGCAGAACTTTAA AAGTGCTCATCATTGGAAAACGTTCTTCGGGGCGAAAACTCTCAAGGATCTTACCGCTGTTGAGATCCAG 5 TTCGATGTAACCCACTCGTGCACCCAACTGATCTTCAGCATCTTTTACTTTCACCAGCGTTTCTGGGTGA GCAAAAACAGGAAGGCAAAATGCCGCAAAAAAGGGAATAAGGGCGACACGGAAATGTTGAATACTCATAC TCTTCCTTTTTCAATATTATTGAAGCATTTATCAGGGTTATTGTCTCATGAGCGGATACATATTTGAATG TATTTAGAAAAATAAACAAATAGGGGTTCCGCGCACATTTCCCCGAAAAGTGCCACCTGACGTCGACGGA TCGGGAGATCGATCTCCCGATCCCCTAGGGTCGACTCTCAGTACAATCTGCTCTGATGCCGCATAGTTAA 10 GCCAGTATCTGCTCCCTGCTTGTGTGTTGGAGGTCGCTGAGTAGTGCGCGAGCAAAATTTAAGCTACAAC AAGGCAAGGCTTGACCGACAATTGCATGAAGAATCTGCTTAGGGTTAGGCGTTTTGCGCTGCTTCGCGAT GTACGGGCCAGATATACGCGTTGACATTGATTATTGACTAGTTATTAATAGTAATCAATTACGGGGTCAT TAGTTCATAGCCCATATATGGAGTTCCGCGTTACATAACTTACGGTAAATGGCCCGCCTGGCTGACCGCC CAACGACCCCCGCCCATTGACGTCAATAATGACGTATGTTCCCATAGTAACGCCAATAGGGACTTTCCAT 15 TGACGTCAATGGGTGGAGTATTTACGGTAAACTGCCCACTTGGCAGTACATCAAGTGTATC By “base editing activity” is meant acting to chemically alter a base within a polynucleotide. In one embodiment, a first base is converted to a second base. In one embodiment, the base editing activity is cytidine deaminase activity, e.g., converting target C^G to T*A. In another embodiment, the base editing activity is adenosine or adenine 20 deaminase activity, e.g., converting A•T to OC. In another embodiment, the base editing activity is cytidine deaminase activity, e.g., converting target C»G to T•A and adenosine or adenine deaminase activity, e.g., converting A»T to G*C. In some embodiments, base editing activity is assessed by efficiency of editing. Base editing efficiency may be measured by any suitable means, for example, by sanger sequencing or next generation sequencing. In some 25 embodiments, base editing efficiency is measured by percentage of total sequencing reads with nucleobase conversion effected by the base editor, for example, percentage of total sequencing reads with target A.T base pair converted to a G.C base pair. In some embodiments, base editing efficiency is measured by percentage of total cells with nucleobase conversion effected by the abse editor, when base editing is performed in a 30 population of cells. The term “base editor system” refers to a system for editing a nucleobase of a target nucleotide sequence. In various embodiments, the base editor system comprises (1) a polynucleotide programmable nucleotide binding domain (e.g. Cas9); (2) a deaminase domain (e.g. an adenosine deaminase) for deaminating said nucleobase; and (3) one or more 35 guide polynucleotide (e.g., guide RNA). In some embodiments, the polynucleotide programmable nucleotide binding domain is a polynucleotide programmable DNA binding 2020221355   24 Feb 2026 domain. In some embodiments, the base editor is an adenine or adenosine base editor (ABE). In some embodiments, the base editor system is ABE8. In some embodiments, a base editor system may comprise more than one base editing component. For example, a base editor system may include more than one deaminase. In 5 some embodiments, a base editor system may include one or more adenosine deaminases. In some embodiments, a single guide polynucleotide may be utilized to target different deaminases to a target nucleic acid sequence. In some embodiments, a single pair of guide polynucleotides may be utilized to target different deaminases to a target nucleic acid sequence. 10          The deaminase domain and the polynucleotide programmable nucleotide binding component of a base editor system may be associated with each other covalently or non-covalently, or any combination of associations and interactions thereof. For example, in some embodiments, a deaminase domain can be targeted to a target nucleotide sequence by a polynucleotide programmable nucleotide binding domain. In some embodiments, a 15 polynucleotide programmable nucleotide binding domain can be fused or linked to a deaminase domain. In some embodiments, a polynucleotide programmable nucleotide binding domain can target a deaminase domain to a target nucleotide sequence by non-covalently interacting with or associating with the deaminase domain. For example, in some embodiments, the deaminase domain can comprise an additional heterologous portion or 20 domain that is capable of interacting with, associating with, or capable of forming a complex with an additional heterologous portion or domain that is part of a polynucleotide programmable nucleotide binding domain. In some embodiments, the additional heterologous portion may be capable of binding to, interacting with, associating with, or forming a complex with a polypeptide. In some embodiments, the additional heterologous 25 portion may be capable of binding to, interacting with, associating with, or forming a complex with a polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a guide polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a polypeptide linker. In some embodiments, the additional heterologous portion may be capable of binding to a 30 polynucleotide linker. The additional heterologous portion may be a protein domain. In some embodiments, the additional heterologous portion may be a K Homology (KH) domain, a MS2 coat protein domain, a PP7 coat protein domain, a SfMu Com coat protein domain, a 2020221355   24 Feb 2026 steril alpha motif, a telomerase Ku binding motif and Ku protein, a telomerase Sm7 binding motif and Sm7 protein, or a RNA recognition motif. A base editor system may further comprise a guide polynucleotide component. It should be appreciated that components of the base editor system may be associated with each 5 other via covalent bonds, noncovalent interactions, or any combination of associations and interactions thereof. In some embodiments, a deaminase domain can be targeted to a target nucleotide sequence by a guide polynucleotide. For example, in some embodiments, the deaminase domain can comprise an additional heterologous portion or domain (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) that is capable of 10 interacting with, associating with, or capable of forming a complex with a portion or segment (e.g., a polynucleotide motif) of a guide polynucleotide. In some embodiments, the additional heterologous portion or domain (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) can be fused or linked to the deaminase domain. In some embodiments, the additional heterologous portion may be capable of binding to, interacting 15 with, associating with, or forming a complex with a polypeptide. In some embodiments, the additional heterologous portion may be capable of binding to, interacting with, associating with, or forming a complex with a polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a guide polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a polypeptide 20 linker. In some embodiments, the additional heterologous portion may be capable of binding to a polynucleotide linker. The additional heterologous portion may be a protein domain. In some embodiments, the additional heterologous portion may be a K Homology (KH) domain, a MS2 coat protein domain, a PP7 coat protein domain, a SfMu Com coat protein domain, a sterile alpha motif, a telomerase Ku binding motif and Ku protein, a telomerase Sm7 binding 25 motif and Sm7 protein, or a RNA recognition motif. In some embodiments, a base editor system can further comprise an inhibitor of base excision repair (BER) component. It should be appreciated that components of the base editor system may be associated with each other via covalent bonds, noncovalent interactions, or any combination of associations and interactions thereof. The inhibitor of BER component 30 may comprise a BER inhibitor. In some embodiments, the inhibitor of BER can be a uracil DNA glycosylase inhibitor (UGI). In some embodiments, the inhibitor of BER can be an inosine BER inhibitor. In some embodiments, the inhibitor of BER can be targeted to the target nucleotide sequence by the polynucleotide programmable nucleotide binding domain. 2020221355   24 Feb 2026 In some embodiments, a polynucleotide programmable nucleotide binding domain can be fused or linked to an inhibitor of BER. In some embodiments, a polynucleotide programmable nucleotide binding domain can be fused or linked to a deaminase domain and an inhibitor of BER. In some embodiments, a polynucleotide programmable nucleotide 5 binding domain can target an inhibitor of BER to a target nucleotide sequence by non-covalently interacting with or associating with the inhibitor of BER. For example, in some embodiments, the inhibitor of BER component can comprise an additional heterologous portion or domain that is capable of interacting with, associating with, or capable of forming a complex with an additional heterologous portion or domain that is part of a polynucleotide 10 programmable nucleotide binding domain. In some embodiments, the inhibitor of BER can be targeted to the target nucleotide sequence by the guide polynucleotide. For example, in some embodiments, the inhibitor of BER can comprise an additional heterologous portion or domain (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) that is capable of interacting with, 15 associating with, or capable of forming a complex with a portion or segment (e.g., a polynucleotide motif) of a guide polynucleotide. In some embodiments, the additional heterologous portion or domain of the guide polynucleotide (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) can be fused or linked to the inhibitor of BER. In some embodiments, the additional heterologous portion may be capable of binding 20 to, interacting with, associating with, or forming a complex with a polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a guide polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a polypeptide linker. In some embodiments, the additional heterologous portion may be capable of binding to a polynucleotide linker. The additional heterologous portion 25 may be a protein domain. In some embodiments, the additional heterologous portion may be a K Homology (KH) domain, a MS2 coat protein domain, a PP7 coat protein domain, a SfMu Com coat protein domain, a sterile alpha motif, a telomerase Ku binding motif and Ku protein, a telomerase Sm7 binding motif and Sm7 protein, or an RNA recognition motif. The term “Cas9” or “Cas9 domain” refers to an RNA guided nuclease comprising a 30 Cas9 protein, or a fragment thereof (e.g., a protein comprising an active, inactive, or partially active DNA cleavage domain of Cas9, and / or the gRNA binding domain of Cas9). A Cas9 nuclease is also referred to sometimes as a Casnl nuclease or a CRISPR (clustered regularly interspaced short palindromic repeat) associated nuclease. CRISPR is an adaptive immune 2020221355   24 Feb 2026 system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain spacers, sequences complementary to antecedent mobile elements, and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). In type II CRISPR 5 systems correct processing of pre-crRNA requires a trans-encoded small RNA (tracrRNA), endogenous ribonuclease 3 (rnc) and a Cas9 protein. The tracrRNA serves as a guide for ribonuclease 3-aided processing of pre-crRNA. Subsequently, Cas9 / crRNA / tracrRNA endonucleolytically cleaves linear or circular dsDNA target complementary to the spacer. The target strand not complementary to crRNA is first cut endonucleolytically, then trimmed 10   3'-5' exonucleolytically. In nature, DNA-binding and cleavage typically requires protein and both RNAs. However, single guide RNAs (“sgRNA”, or simply “gRNA”) can be engineered so as to incorporate aspects of both the crRNA and tracrRNA into a single RNA species. See, e.g., Jinek M., Chylinski K., Fonfara I., Hauer M., Doudna J.A., Charpentier E. Science 337:816-821(2012), the entire contents of which is hereby incorporated by reference. Cas9 15 recognizes a short motif in the CRISPR repeat sequences (the PAM or protospacer adjacent motif) to help distinguish self versus non-self. Cas9 nuclease sequences and structures are well known to those of skill in the art (see, e.g., “Complete genome sequence of an M1 strain of Streptococcus pyogenes.” Ferretti et al., J.J., McShan W.M., Ajdic D.J., Savic D.J., Savic G., Lyon K., Primeaux C., Sezate S., Suvorov A.N., Kenton S., Lai H.S., Lin S.P., Qian Y., 20 Jia H.G., Najar F.Z., Ren Q., Zhu H., Song L., White J., Yuan X., Clifton S.W., Roe B.A., McLaughlin R.E., Proc. Natl. Acad. Sci. U.S.A. 98:4658-4663(2001); “CRISPR RNA maturation by trans-encoded small RNA and host factor RNase III.” Deltcheva E., Chylinski K., Sharma C.M., Gonzales K., Chao Y., Pirzada Z.A., Eckert M.R., Vogel J., Charpentier E., Nature 471:602-607(2011); and “A programmable dual-RNA-guided DNA endonuclease in 25 adaptive bacterial immunity.” Jinek M., Chylinski K., Fonfara I., Hauer M., Doudna J.A., Charpentier E. Science 337:816-821(2012), the entire contents of each of which are incorporated herein by reference). Cas9 orthologs have been described in various species, including, but not limited to, S. pyogenes and S. thermophilus. Additional suitable Cas9 nucleases and sequences will be apparent to those of skill in the art based on this disclosure, 30 and such Cas9 nucleases and sequences include Cas9 sequences from the organisms and loci disclosed in Chylinski, Rhun, and Charpentier, “The tracrRNA and Cas9 families of type II CRISPR-Cas immunity systems” (2013) RNA Biology 10:5, 726-737; the entire contents of which are incorporated herein by reference. 2020221355   24 Feb 2026 An exemplary Cas9, is Streptococcus pyogenes Cas9 (spCas9), the amino acid sequence of which is provided below: MDKKYSIGLDIGTNSVGWAVITDDYKVPSKKFKVLGNTDRHSIKKNLIGALLFGSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD 5 EVAYHEKYPTIYHLRKKLADSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQIYNQLFEENPINASRVDAKAILSARLSKSRRLENLIAQLPGEKRNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNS EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK 10 DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGAYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDRGMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGHSLHEQIANLAGSPAIKKGILQTVKIV 15 DELVKVMGHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFIKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV GTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANG 20  EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGF SKESILPKRNSD KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL 25 GGD (single underline: HNH domain; double underline: RuvC domain) A nuclease-inactivated Cas9 protein may interchangeably be referred to as a “dCas9” protein (for nuclease-“dead” Cas9) or catalytically inactive Cas9. Methods for generating a Cas9 protein (or a fragment thereof) having an inactive DNA cleavage domain are known 30 (See, e.g., Jinek et al., Science. 337:816-821(2012); Qi et al., “Repurposing CRISPR as an RNA-Guided Platform for Sequence-Specific Control of Gene Expression” (2013) Cell. 28;152(5):1173-83, the entire contents of each of which are incorporated herein by reference). For example, the DNA cleavage domain of Cas9 is known to include two subdomains, the HNH nuclease subdomain and the RuvC1 subdomain. The HNH subdomain 2020221355   24 Feb 2026 cleaves the strand complementary to the gRNA, whereas the RuvC1 subdomain cleaves the non-complementary strand. Mutations within these subdomains can silence the nuclease activity of Cas9. For example, the mutations D10A and H840A completely inactivate the nuclease activity of S. pyogenes Cas9 (Jinek et al., Science. 337:816-821(2012); Qi et al., 5   Cell. 28;152(5):1173-83 (2013)). In some embodiments, a Cas9 nuclease has an inactive (e.g., an inactivated) DNA cleavage domain, that is, the Cas9 is a nickase, referred to as an “nCas9” protein (for “nickase” Cas9). In some embodiments, proteins comprising fragments of Cas9 are provided. For example, in some embodiments, a protein comprises one of two Cas9 domains: (1) the gRNA binding domain of Cas9; or (2) the DNA cleavage domain of 10 Cas9. In some embodiments, proteins comprising Cas9 or fragments thereof are referred to as “Cas9 variants.” A Cas9 variant shares homology to Cas9, or a fragment thereof. For example, a Cas9 variant is at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 96% identical, at least about 97% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% 15 identical, or at least about 99.9% identical to wild-type Cas9. In some embodiments, the Cas9 variant may have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 21, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 or more amino acid changes compared to wild-type Cas9. In some embodiments, the Cas9 variant comprises a fragment of Cas9 (e.g., a gRNA binding domain 20 or a DNA-cleavage domain), such that the fragment is at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 96% identical, at least about 97% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical to the corresponding fragment of wild-type Cas9. In some embodiments, the fragment is at least 30%, at least 25   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% identical, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% of the amino acid length of a corresponding wild-type Cas9. In some embodiments, the fragment is at least 100 amino acids in length. In some 30 embodiments, the fragment is at least 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, or at least 1300 amino acids in length. 2020221355   24 Feb 2026 In some embodiments, wild-type Cas9 corresponds to Cas9 from Streptococcus pyogenes (NCBI Reference Sequence: NC_017053.1, nucleotide and amino acid sequences as follows). ATGGATAAGAAATACTCAATAGGCTTAGATATCGGCACAAATAGCGTCGGATGGGCGGTGAT 5 CACTGATGATTATAAGGTTCCGTCTAAAAAGTTCAAGGTTCTGGGAAATACAGACCGCCACA GTATCAAAAAAAATCTTATAGGGGCTCTTTTATTTGGCAGTGGAGAGACAGCGGAAGCGACT CGTCTCAAACGGACAGCTCGTAGAAGGTATACACGTCGGAAGAATCGTATTTGTTATCTACA GGAGATTTTTTCAAATGAGATGGCGAAAGTAGATGATAGTTTCTTTCATCGACTTGAAGAGT CTTTTTTGGTGGAAGAAGACAAGAAGCATGAACGTCATCCTATTTTTGGAAATATAGTAGAT 10 GAAGTTGCTTATCATGAGAAATATCCAACTATCTATCATCTGCGAAAAAAATTGGCAGATTC TACTGATAAAGCGGATTTGCGCTTAATCTATTTGGCCTTAGCGCATATGATTAAGTTTCGTG GTCATTTTTTGATTGAGGGAGATTTAAATCCTGATAATAGTGATGTGGACAAACTATTTATC CAGTTGGTACAAATCTACAATCAATTATTTGAAGAAAACCCTATTAACGCAAGTAGAGTAGA TGCTAAAGCGATTCTTTCTGCACGATTGAGTAAATCAAGACGATTAGAAAATCTCATTGCTC 15 AGCTCCCCGGTGAGAAGAGAAATGGCTTGTTTGGGAATCTCATTGCTTTGTCATTGGGATTG ACCCCTAATTTTAAATCAAATTTTGATTTGGCAGAAGATGCTAAATTACAGCTTTCAAAAGA TACTTACGATGATGATTTAGATAATTTATTGGCGCAAATTGGAGATCAATATGCTGATTTGT TTTTGGCAGCTAAGAATTTATCAGATGCTATTTTACTTTCAGATATCCTAAGAGTAAATAGT GAAATAACTAAGGCTCCCCTATCAGCTTCAATGATTAAGCGCTACGATGAACATCATCAAGA 20 CTTGACTCTTTTAAAAGCTTTAGTTCGACAACAACTTCCAGAAAAGTATAAAGAAATCTTTT TTGATCAATCAAAAAACGGATATGCAGGTTATATTGATGGGGGAGCTAGCCAAGAAGAATTT TATAAATTTATCAAACCAATTTTAGAAAAAATGGATGGTACTGAGGAATTATTGGTGAAACT AAATCGTGAAGATTTGCTGCGCAAGCAACGGACCTTTGACAACGGCTCTATTCCCCATCAAA TTCACTTGGGTGAGCTGCATGCTATTTTGAGAAGACAAGAAGACTTTTATCCATTTTTAAAA 25 GACAATCGTGAGAAGATTGAAAAAATCTTGACTTTTCGAATTCCTTATTATGTTGGTCCATT GGCGCGTGGCAATAGTCGTTTTGCATGGATGACTCGGAAGTCTGAAGAAACAATTACCCCAT GGAATTTTGAAGAAGTTGTCGATAAAGGTGCTTCAGCTCAATCATTTATTGAACGCATGACA AACTTTGATAAAAATCTTCCAAATGAAAAAGTACTACCAAAACATAGTTTGCTTTATGAGTA TTTTACGGTTTATAACGAATTGACAAAGGTCAAATATGTTACTGAGGGAATGCGAAAACCAG 30 CATTTCTTTCAGGTGAACAGAAGAAAGCCATTGTTGATTTACTCTTCAAAACAAATCGAAAA GTAACCGTTAAGCAATTAAAAGAAGATTATTTCAAAAAAATAGAATGTTTTGATAGTGTTGA AATTTCAGGAGTTGAAGATAGATTTAATGCTTCATTAGGCGCCTACCATGATTTGCTAAAAA TTATTAAAGATAAAGATTTTTTGGATAATGAAGAAAATGAAGATATCTTAGAGGATATTGTT TTAACATTGACCTTATTTGAAGATAGGGGGATGATTGAGGAAAGACTTAAAACATATGCTCA 2020221355   24 Feb 2026 CCTCTTTGATGATAAGGTGATGAAACAGCTTAAACGTCGCCGTTATACTGGTTGGGGACGTT TGTCTCGAAAATTGATTAATGGTATTAGGGATAAGCAATCTGGCAAAACAATATTAGATTTT TTGAAATCAGATGGTTTTGCCAATCGCAATTTTATGCAGCTGATCCATGATGATAGTTTGAC ATTTAAAGAAGATATTCAAAAAGCACAGGTGTCTGGACAAGGCCATAGTTTACATGAACAGA 5 TTGCTAACTTAGCTGGCAGTCCTGCTATTAAAAAAGGTATTTTACAGACTGTAAAAATTGTT GATGAACTGGTCAAAGTAATGGGGCATAAGCCAGAAAATATCGTTATTGAAATGGCACGTGA AAATCAGACAACTCAAAAGGGCCAGAAAAATTCGCGAGAGCGTATGAAACGAATCGAAGAAG GTATCAAAGAATTAGGAAGTCAGATTCTTAAAGAGCATCCTGTTGAAAATACTCAATTGCAA AATGAAAAGCTCTATCTCTATTATCTACAAAATGGAAGAGACATGTATGTGGACCAAGAATT 10 AGATATTAATCGTTTAAGTGATTATGATGTCGATCACATTGTTCCACAAAGTTTCATTAAAG ACGATTCAATAGACAATAAGGTACTAACGCGTTCTGATAAAAATCGTGGTAAATCGGATAAC GTTCCAAGTGAAGAAGTAGTCAAAAAGATGAAAAACTATTGGAGACAACTTCTAAACGCCAA GTTAATCACTCAACGTAAGTTTGATAATTTAACGAAAGCTGAACGTGGAGGTTTGAGTGAAC TTGATAAAGCTGGTTTTATCAAACGCCAATTGGTTGAAACTCGCCAAATCACTAAGCATGTG 15 GCACAAATTTTGGATAGTCGCATGAATACTAAATACGATGAAAATGATAAACTTATTCGAGA GGTTAAAGTGATTACCTTAAAATCTAAATTAGTTTCTGACTTCCGAAAAGATTTCCAATTCT ATAAAGTACGTGAGATTAACAATTACCATCATGCCCATGATGCGTATCTAAATGCCGTCGTT GGAACTGCTTTGATTAAGAAATATCCAAAACTTGAATCGGAGTTTGTCTATGGTGATTATAA AGTTTATGATGTTCGTAAAATGATTGCTAAGTCTGAGCAAGAAATAGGCAAAGCAACCGCAA 20 AATATTTCTTTTACTCTAATATCATGAACTTCTTCAAAACAGAAATTACACTTGCAAATGGA GAGATTCGCAAACGCCCTCTAATCGAAACTAATGGGGAAACTGGAGAAATTGTCTGGGATAA AGGGCGAGATTTTGCCACAGTGCGCAAAGTATTGTCCATGCCCCAAGTCAATATTGTCAAGA AAACAGAAGTACAGACAGGCGGATTCTCCAAGGAGTCAATTTTACCAAAAAGAAATTCGGAC AAGCTTATTGCTCGTAAAAAAGACTGGGATCCAAAAAAATATGGTGGTTTTGATAGTCCAAC 25 GGTAGCTTATTCAGTCCTAGTGGTTGCTAAGGTGGAAAAAGGGAAATCGAAGAAGTTAAAAT CCGTTAAAGAGTTACTAGGGATCACAATTATGGAAAGAAGTTCCTTTGAAAAAAATCCGATT GACTTTTTAGAAGCTAAAGGATATAAGGAAGTTAAAAAAGACTTAATCATTAAACTACCTAA ATATAGTCTTTTTGAGTTAGAAAACGGTCGTAAACGGATGCTGGCTAGTGCCGGAGAATTAC AAAAAGGAAATGAGCTGGCTCTGCCAAGCAAATATGTGAATTTTTTATATTTAGCTAGTCAT 30 TATGAAAAGTTGAAGGGTAGTCCAGAAGATAACGAACAAAAACAATTGTTTGTGGAGCAGCA TAAGCATTATTTAGATGAGATTATTGAGCAAATCAGTGAATTTTCTAAGCGTGTTATTTTAG CAGATGCCAATTTAGATAAAGTTCTTAGTGCATATAACAAACATAGAGACAAACCAATACGT GAACAAGCAGAAAATATTATTCATTTATTTACGTTGACGAATCTTGGAGCTCCCGCTGCTTT TAAATATTTTGATACAACAATTGATCGTAAACGATATACGTCTACAAAAGAAGTTTTAGATG 2020221355   24 Feb 2026 CCACTCTTATCCATCAATCCATCACTGGTCTTTATGAAACACGCATTGATTTGAGTCAGCTA GGAGGTGACTGA MDKKYSIGLDIGTNSVGWAVITDDYKVPSKKFKVLGNTDRHSIKKNLIGALLFGSGETAEAT 5 RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLADSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQIYNQLFEENPINASRVDAKAILSARLSKSRRLENLIAQLPGEKRNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNS EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF 10 YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGAYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDRGMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF 15 LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGHSLHEQIANLAGSPAIKKGILQTVKIV DELVKVMGHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFIKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV 20 GTALXKKYPKLESEFVYGDYKVYDVRKMIAKSEQEXGKATAKYFFYSN1MNFFKTEXTLANG EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESIL PKRN S D KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR 25 EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL GGD (single underline: HNH domain; double underline: RuvC domain) In some embodiments, wild-type Cas9 corresponds to, or comprises the following nucleotide and / or amino acid sequences: 30 ATGGATAAAAAGTATTCTATTGGTTTAGACATCGGCACTAATTCCGTTGGATGGGCTGTCAT AACCGATGAATACAAAGTACCTTCAAAGAAATTTAAGGTGTTGGGGAACACAGACCGTCATT CGATTAAAAAGAATCTTATCGGTGCCCTCCTATTCGATAGTGGCGAAACGGCAGAGGCGACT CGCCTGAAACGAACCGCTCGGAGAAGGTATACACGTCGCAAGAACCGAATATGTTACTTACA AGAAATTTTTAGCAATGAGATGGCCAAAGTTGACGATTCTTTCTTTCACCGTTTGGAAGAGT 2020221355   24 Feb 2026 CCTTCCTTGTCGAAGAGGACAAGAAACATGAACGGCACCCCATCTTTGGAAACATAGTAGAT GAGGTGGCATATCATGAAAAGTACCCAACGATTTATCACCTCAGAAAAAAGCTAGTTGACTC AACTGATAAAGCGGACCTGAGGTTAATCTACTTGGCTCTTGCCCATATGATAAAGTTCCGTG GGCACTTTCTCATTGAGGGTGATCTAAATCCGGACAACTCGGATGTCGACAAACTGTTCATC 5 CAGTTAGTACAAACCTATAATCAGTTGTTTGAAGAGAACCCTATAAATGCAAGTGGCGTGGA TGCGAAGGCTATTCTTAGCGCCCGCCTCTCTAAATCCCGACGGCTAGAAAACCTGATCGCAC AATTACCCGGAGAGAAGAAAAATGGGTTGTTCGGTAACCTTATAGCGCTCTCACTAGGCCTG ACACCAAATTTTAAGTCGAACTTCGACTTAGCTGAAGATGCCAAATTGCAGCTTAGTAAGGA CACGTACGATGACGATCTCGACAATCTACTGGCACAAATTGGAGATCAGTATGCGGACTTAT 10 TTTTGGCTGCCAAAAACCTTAGCGATGCAATCCTCCTATCTGACATACTGAGAGTTAATACT GAGATTACCAAGGCGCCGTTATCCGCTTCAATGATCAAAAGGTACGATGAACATCACCAAGA CTTGACACTTCTCAAGGCCCTAGTCCGTCAGCAACTGCCTGAGAAATATAAGGAAATATTCT TTGATCAGTCGAAAAACGGGTACGCAGGTTATATTGACGGCGGAGCGAGTCAAGAGGAATTC TACAAGTTTATCAAACCCATATTAGAGAAGATGGATGGGACGGAAGAGTTGCTTGTAAAACT 15 CAATCGCGAAGATCTACTGCGAAAGCAGCGGACTTTCGACAACGGTAGCATTCCACATCAAA TCCACTTAGGCGAATTGCATGCTATACTTAGAAGGCAGGAGGATTTTTATCCGTTCCTCAAA GACAATCGTGAAAAGATTGAGAAAATCCTAACCTTTCGCATACCTTACTATGTGGGACCCCT GGCCCGAGGGAACTCTCGGTTCGCATGGATGACAAGAAAGTCCGAAGAAACGATTACTCCAT GGAATTTTGAGGAAGTTGTCGATAAAGGTGCGTCAGCTCAATCGTTCATCGAGAGGATGACC 20 AACTTTGACAAGAATTTACCGAACGAAAAAGTATTGCCTAAGCACAGTTTACTTTACGAGTA TTTCACAGTGTACAATGAACTCACGAAAGTTAAGTATGTCACTGAGGGCATGCGTAAACCCG CCTTTCTAAGCGGAGAACAGAAGAAAGCAATAGTAGATCTGTTATTCAAGACCAACCGCAAA GTGACAGTTAAGCAATTGAAAGAGGACTACTTTAAGAAAATTGAATGCTTCGATTCTGTCGA GATCTCCGGGGTAGAAGATCGATTTAATGCGTCACTTGGTACGTATCATGACCTCCTAAAGA 25 TAATTAAAGATAAGGACTTCCTGGATAACGAAGAGAATGAAGATATCTTAGAAGATATAGTG TTGACTCTTACCCTCTTTGAAGATCGGGAAATGATTGAGGAAAGACTAAAAACATACGCTCA CCTGTTCGACGATAAGGTTATGAAACAGTTAAAGAGGCGTCGCTATACGGGCTGGGGACGAT TGTCGCGGAAACTTATCAACGGGATAAGAGACAAGCAAAGTGGTAAAACTATTCTCGATTTT CTAAAGAGCGACGGCTTCGCCAATAGGAACTTTATGCAGCTGATCCATGATGACTCTTTAAC 30 CTTCAAAGAGGATATACAAAAGGCACAGGTTTCCGGACAAGGGGACTCATTGCACGAACATA TTGCGAATCTTGCTGGTTCGCCAGCCATCAAAAAGGGCATACTCCAGACAGTCAAAGTAGTG GATGAGCTAGTTAAGGTCATGGGACGTCACAAACCGGAAAACATTGTAATCGAGATGGCACG CGAAAATCAAACGACTCAGAAGGGGCAAAAAAACAGTCGAGAGCGGATGAAGAGAATAGAAG AGGGTATTAAAGAACTGGGCAGCCAGATCTTAAAGGAGCATCCTGTGGAAAATACCCAATTG 2020221355   24 Feb 2026 CAGAACGAGAAACTTTACCTCTATTACCTACAAAATGGAAGGGACATGTATGTTGATCAGGA ACTGGACATAAACCGTTTATCTGATTACGACGTCGATCACATTGTACCCCAATCCTTTTTGA AGGACGATTCAATCGACAATAAAGTGCTTACACGCTCGGATAAGAACCGAGGGAAAAGTGAC AATGTTCCAAGCGAGGAAGTCGTAAAGAAAATGAAGAACTATTGGCGGCAGCTCCTAAATGC 5 GAAACTGATAACGCAAAGAAAGTTCGATAACTTAACTAAAGCTGAGAGGGGTGGCTTGTCTG AACTTGACAAGGCCGGATTTATTAAACGTCAGCTCGTGGAAACCCGCCAAATCACAAAGCAT GTTGCACAGATACTAGATTCCCGAATGAATACGAAATACGACGAGAACGATAAGCTGATTCG GGAAGTCAAAGTAATCACTTTAAAGTCAAAATTGGTGTCGGACTTCAGAAAGGATTTTCAAT TCTATAAAGTTAGGGAGATAAATAACTACCACCATGCGCACGACGCTTATCTTAATGCCGTC 10 GTAGGGACCGCACTCATTAAGAAATACCCGAAGCTAGAAAGTGAGTTTGTGTATGGTGATTA CAAAGTTTATGACGTCCGTAAGATGATCGCGAAAAGCGAACAGGAGATAGGCAAGGCTACAG CCAAATACTTCTTTTATTCTAACATTATGAATTTCTTTAAGACGGAAATCACTCTGGCAAAC GGAGAGATACGCAAACGACCTTTAATTGAAACCAATGGGGAGACAGGTGAAATCGTATGGGA TAAGGGCCGGGACTTCGCGACGGTGAGAAAAGTTTTGTCCATGCCCCAAGTCAACATAGTAA 15 AGAAAACTGAGGTGCAGACCGGAGGGTTTTCAAAGGAATCGATTCTTCCAAAAAGGAATAGT GATAAGCTCATCGCTCGTAAAAAGGACTGGGACCCGAAAAAGTACGGTGGCTTCGATAGCCC TACAGTTGCCTATTCTGTCCTAGTAGTGGCAAAAGTTGAGAAGGGAAAATCCAAGAAACTGA AGTCAGTCAAAGAATTATTGGGGATAACGATTATGGAGCGCTCGTCTTTTGAAAAGAACCCC ATCGACTTCCTTGAGGCGAAAGGTTACAAGGAAGTAAAAAAGGATCTCATAATTAAACTACC 20 AAAGTATAGTCTGTTTGAGTTAGAAAATGGCCGAAAACGGATGTTGGCTAGCGCCGGAGAGC TTCAAAAGGGGAACGAACTCGCACTACCGTCTAAATACGTGAATTTCCTGTATTTAGCGTCC CATTACGAGAAGTTGAAAGGTTCACCTGAAGATAACGAACAGAAGCAACTTTTTGTTGAGCA GCACAAACATTATCTCGACGAAATCATAGAGCAAATTTCGGAATTCAGTAAGAGAGTCATCC TAGCTGATGCCAATCTGGACAAAGTATTAAGCGCATACAACAAGCACAGGGATAAACCCATA 25 CGTGAGCAGGCGGAAAATATTATCCATTTGTTTACTCTTACCAACCTCGGCGCTCCAGCCGC ATTCAAGTATTTTGACACAACGATAGATCGCAAACGATACACTTCTACCAAGGAGGTGCTAG ACGCGACACTGATTCACCAATCCATCACGGGATTATATGAAACTCGGATAGATTTGTCACAG CTTGGGGGTGACGGATCCCCCAAGAAGAAGAGGAAAGTCTCGAGCGACTACAAAGACCATGA CGGTGATTATAAAGATCATGACATCGATTACAAGGATGACGATGACAAGGCTGCAGGA 30 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL 2020221355   24 Feb 2026 TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT 5 NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL 10 QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS 15 DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD 20 (single underline: HNH domain; double underline: RuvC domain) In some embodiments, wild-type Cas9 corresponds to Cas9 from Streptococcus pyogenes (NCBI Reference Sequence: NC_002737.2 (nucleotide sequence as follows); and Uniprot Reference Sequence: Q99ZW2 (amino acid sequence as follows). ATGGATAAGAAATACTCAATAGGCTTAGATATCGGCACAAATAGCGTCGGATGGGCGGTGAT 25 CACTGATGAATATAAGGTTCCGTCTAAAAAGTTCAAGGTTCTGGGAAATACAGACCGCCACA GTATCAAAAAAAATCTTATAGGGGCTCTTTTATTTGACAGTGGAGAGACAGCGGAAGCGACT CGTCTCAAACGGACAGCTCGTAGAAGGTATACACGTCGGAAGAATCGTATTTGTTATCTACA GGAGATTTTTTCAAATGAGATGGCGAAAGTAGATGATAGTTTCTTTCATCGACTTGAAGAGT CTTTTTTGGTGGAAGAAGACAAGAAGCATGAACGTCATCCTATTTTTGGAAATATAGTAGAT 30 GAAGTTGCTTATCATGAGAAATATCCAACTATCTATCATCTGCGAAAAAAATTGGTAGATTC TACTGATAAAGCGGATTTGCGCTTAATCTATTTGGCCTTAGCGCATATGATTAAGTTTCGTG GTCATTTTTTGATTGAGGGAGATTTAAATCCTGATAATAGTGATGTGGACAAACTATTTATC CAGTTGGTACAAACCTACAATCAATTATTTGAAGAAAACCCTATTAACGCAAGTGGAGTAGA TGCTAAAGCGATTCTTTCTGCACGATTGAGTAAATCAAGACGATTAGAAAATCTCATTGCTC 2020221355   24 Feb 2026 AGCTCCCCGGTGAGAAGAAAAATGGCTTATTTGGGAATCTCATTGCTTTGTCATTGGGTTTG ACCCCTAATTTTAAATCAAATTTTGATTTGGCAGAAGATGCTAAATTACAGCTTTCAAAAGA TACTTACGATGATGATTTAGATAATTTATTGGCGCAAATTGGAGATCAATATGCTGATTTGT TTTTGGCAGCTAAGAATTTATCAGATGCTATTTTACTTTCAGATATCCTAAGAGTAAATACT 5 GAAATAACTAAGGCTCCCCTATCAGCTTCAATGATTAAACGCTACGATGAACATCATCAAGA CTTGACTCTTTTAAAAGCTTTAGTTCGACAACAACTTCCAGAAAAGTATAAAGAAATCTTTT TTGATCAATCAAAAAACGGATATGCAGGTTATATTGATGGGGGAGCTAGCCAAGAAGAATTT TATAAATTTATCAAACCAATTTTAGAAAAAATGGATGGTACTGAGGAATTATTGGTGAAACT AAATCGTGAAGATTTGCTGCGCAAGCAACGGACCTTTGACAACGGCTCTATTCCCCATCAAA 10 TTCACTTGGGTGAGCTGCATGCTATTTTGAGAAGACAAGAAGACTTTTATCCATTTTTAAAA GACAATCGTGAGAAGATTGAAAAAATCTTGACTTTTCGAATTCCTTATTATGTTGGTCCATT GGCGCGTGGCAATAGTCGTTTTGCATGGATGACTCGGAAGTCTGAAGAAACAATTACCCCAT GGAATTTTGAAGAAGTTGTCGATAAAGGTGCTTCAGCTCAATCATTTATTGAACGCATGACA AACTTTGATAAAAATCTTCCAAATGAAAAAGTACTACCAAAACATAGTTTGCTTTATGAGTA 15 TTTTACGGTTTATAACGAATTGACAAAGGTCAAATATGTTACTGAAGGAATGCGAAAACCAG CATTTCTTTCAGGTGAACAGAAGAAAGCCATTGTTGATTTACTCTTCAAAACAAATCGAAAA GTAACCGTTAAGCAATTAAAAGAAGATTATTTCAAAAAAATAGAATGTTTTGATAGTGTTGA AATTTCAGGAGTTGAAGATAGATTTAATGCTTCATTAGGTACCTACCATGATTTGCTAAAAA TTATTAAAGATAAAGATTTTTTGGATAATGAAGAAAATGAAGATATCTTAGAGGATATTGTT 20 TTAACATTGACCTTATTTGAAGATAGGGAGATGATTGAGGAAAGACTTAAAACATATGCTCA CCTCTTTGATGATAAGGTGATGAAACAGCTTAAACGTCGCCGTTATACTGGTTGGGGACGTT TGTCTCGAAAATTGATTAATGGTATTAGGGATAAGCAATCTGGCAAAACAATATTAGATTTT TTGAAATCAGATGGTTTTGCCAATCGCAATTTTATGCAGCTGATCCATGATGATAGTTTGAC ATTTAAAGAAGACATTCAAAAAGCACAAGTGTCTGGACAAGGCGATAGTTTACATGAACATA 25 TTGCAAATTTAGCTGGTAGCCCTGCTATTAAAAAAGGTATTTTACAGACTGTAAAAGTTGTT GATGAATTGGTCAAAGTAATGGGGCGGCATAAGCCAGAAAATATCGTTATTGAAATGGCACG TGAAAATCAGACAACTCAAAAGGGCCAGAAAAATTCGCGAGAGCGTATGAAACGAATCGAAG AAGGTATCAAAGAATTAGGAAGTCAGATTCTTAAAGAGCATCCTGTTGAAAATACTCAATTG CAAAATGAAAAGCTCTATCTCTATTATCTCCAAAATGGAAGAGACATGTATGTGGACCAAGA 30 ATTAGATATTAATCGTTTAAGTGATTATGATGTCGATCACATTGTTCCACAAAGTTTCCTTA AAGACGATTCAATAGACAATAAGGTCTTAACGCGTTCTGATAAAAATCGTGGTAAATCGGAT AACGTTCCAAGTGAAGAAGTAGTCAAAAAGATGAAAAACTATTGGAGACAACTTCTAAACGC CAAGTTAATCACTCAACGTAAGTTTGATAATTTAACGAAAGCTGAACGTGGAGGTTTGAGTG AACTTGATAAAGCTGGTTTTATCAAACGCCAATTGGTTGAAACTCGCCAAATCACTAAGCAT 2020221355   24 Feb 2026 GTGGCACAAATTTTGGATAGTCGCATGAATACTAAATACGATGAAAATGATAAACTTATTCG AGAGGTTAAAGTGATTACCTTAAAATCTAAATTAGTTTCTGACTTCCGAAAAGATTTCCAAT TCTATAAAGTACGTGAGATTAACAATTACCATCATGCCCATGATGCGTATCTAAATGCCGTC GTTGGAACTGCTTTGATTAAGAAATATCCAAAACTTGAATCGGAGTTTGTCTATGGTGATTA 5 TAAAGTTTATGATGTTCGTAAAATGATTGCTAAGTCTGAGCAAGAAATAGGCAAAGCAACCG CAAAATATTTCTTTTACTCTAATATCATGAACTTCTTCAAAACAGAAATTACACTTGCAAAT GGAGAGATTCGCAAACGCCCTCTAATCGAAACTAATGGGGAAACTGGAGAAATTGTCTGGGA TAAAGGGCGAGATTTTGCCACAGTGCGCAAAGTATTGTCCATGCCCCAAGTCAATATTGTCA AGAAAACAGAAGTACAGACAGGCGGATTCTCCAAGGAGTCAATTTTACCAAAAAGAAATTCG 10 GACAAGCTTATTGCTCGTAAAAAAGACTGGGATCCAAAAAAATATGGTGGTTTTGATAGTCC AACGGTAGCTTATTCAGTCCTAGTGGTTGCTAAGGTGGAAAAAGGGAAATCGAAGAAGTTAA AATCCGTTAAAGAGTTACTAGGGATCACAATTATGGAAAGAAGTTCCTTTGAAAAAAATCCG ATTGACTTTTTAGAAGCTAAAGGATATAAGGAAGTTAAAAAAGACTTAATCATTAAACTACC TAAATATAGTCTTTTTGAGTTAGAAAACGGTCGTAAACGGATGCTGGCTAGTGCCGGAGAAT 15 TACAAAAAGGAAATGAGCTGGCTCTGCCAAGCAAATATGTGAATTTTTTATATTTAGCTAGT CATTATGAAAAGTTGAAGGGTAGTCCAGAAGATAACGAACAAAAACAATTGTTTGTGGAGCA GCATAAGCATTATTTAGATGAGATTATTGAGCAAATCAGTGAATTTTCTAAGCGTGTTATTT TAGCAGATGCCAATTTAGATAAAGTTCTTAGTGCATATAACAAACATAGAGACAAACCAATA CGTGAACAAGCAGAAAATATTATTCATTTATTTACGTTGACGAATCTTGGAGCTCCCGCTGC 20 TTTTAAATATTTTGATACAACAATTGATCGTAAACGATATACGTCTACAAAAGAAGTTTTAG ATGCCACTCTTATCCATCAATCCATCACTGGTCTTTATGAAACACGCATTGATTTGAGTCAG CTAGGAGGTGACTGA MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT 25 RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF 30 YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF 2020221355   24 Feb 2026 LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH 5 VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESIL PKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS 10 HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD (SEQ ID NO: 1. single underline: HNH domain; double underline: RuvC domain) In some embodiments, Cas9 refers to Cas9 from: Corynebacterium ulcerans (NCBI Refs: NC_015683.1, NC_017317.1); Corynebacterium diphtheria (NCBI Refs: 15   NC_016782.1, NC_016786.1); Spiroplasma syrphidicola (NCBI Ref: NC_021284.1); Prevotella intermedia (NCBI Ref: NC_017861.1); Spiroplasma taiwanense (NCBI Ref: NC_021846.1); Streptococcus iniae (NCBI Ref: NC_021314.1); Belliella baltica (NCBI Ref: NC_018010.1); Psychroflexus torquisI (NCBI Ref: NC_018721.1); Streptococcus thermophilus (NCBI Ref: YP_820832.1), Listeria innocua (NCBI Ref: NP_472073.1), 20   Campylobacter jejuni (NCBI Ref: YP_002344900.1) or Neisseria meningitidis (NCBI Ref: YP_002342100.1) or to a Cas9 from any other organism. In some embodiments, the Cas9 is from Neisseria meningitidis (Nme). In some embodiments, the Cas9 is Nme1, Nme2 or Nme3. In some embodiments, the PAM-interacting domains for Nme1, Nme2 or Nme3 are N4GAT, N4CC, and N4CAAA, 25 respectively (see e.g., Edraki, A., et al., A Compact, High-Accuracy Cas9 with a Dinucleotide PAM for In Vivo Genome Editing, Molecular Cell (2018)). An exemplary Neisseria meningitidis Cas9 protein, Nme1Cas9, (NCBI Reference: WP_002235162.1; type II CRISPR RNA-guided endonuclease Cas9) has the following amino acid sequence: 1 maafkpnpin yilgldigia svgwamveid edenpiclid Igvrvferae vpktgdslam 30          61 arrlarsvrr ltrrrahrll rarrllkreg vlqaadfden glikslpntp wqlraaaldr 121 kltplewsav llhlikhrgy lsqrkneget adkelgallk gvadnahalq tgdfrtpael 181 alnkfekesg hirnqrgdys htfsrkdlqa elillfekqk efgnphvsgg lkegietllm 241 tqrpalsgda vqkmlghctf epaepkaakn tytaerfiwl tklnnlrile qgserpltdt 301 eratlmdepy rkskltyaqa rkllgledta ffkglrygkd naeastlmem kayhaisral 35         361 ekeglkdkks plnlspelqd eigtafslfk tdeditgrlk driqpeilea llkhisfdkf 2020221355   24 Feb 2026 421 vqislkalrr ivplmeqgkr ydeacaeiyg dhygkkntee kiylppipad eirnpvvlra 481 Isqarkving vvrrygspar ihietarevg ksfkdrkeie krqeenrkdr ekaaakfrey 541 fpnfvgepks kdilklrlye qqhgkclysg keinlgrlne kgyveidhal pfsrtwddsf 601 nnkvlvlgse nqnkgnqtpy eyfngkdnsr ewqefkarve tsrfprskkq rillqkfded 5         661 gfkernlndt ryvnrflcqf vadrmrltgk gkkrvfasng qitnllrgfw glrkvraend 721 rhhaldavvv acstvamqqk itrfvrykem nafdgktidk etgevlhqkt hfpqpweffa 781 qevmirvfgk pdgkpefeea dtpeklrtll aeklssrpea vheyvtplfv srapnrkmsg 841 qghmetvksa krldegvsvl rvpltqlklk dlekmvnrer epklyealka rleahkddpa 901 kafaepfyky dkagnrtqqv kavrveqvqk tgvwvrnhng iadnatmvrv dvfekgdkyy 10         961 lvpiyswqva kgilpdravv qgkdeedwql iddsfnfkfs lhpndlvevi tkkarmfgyf 1021 aschrgtgni nirihdldhk igkngilegi gvktalsfqk yqidelgkei rpcrlkkrpp 1081 vr Another exemplary Neisseria meningitidis Cas9 protein, Nme2Cas9, (NCBI Reference: WP_002230835; type II CRISPR RNA-guided endonuclease Cas9) has the 15 following amino acid sequence: 1 maafkpnpin yilgldigia svgwamveid eeenpirlid lgvrvferae vpktgdslam 61 arrlarsvrr ltrrrahrll rarrllkreg vlqaadfden glikslpntp wqlraaaldr 121 kltplewsav llhlikhrgy lsqrkneget adkelgallk gvannahalq tgdfrtpael 181 alnkfekesg hirnqrgdys htfsrkdlqa elillfekqk efgnphvsgg lkegietllm 20         241 tqrpalsgda vqkmlghctf epaepkaakn tytaerfiwl tklnnlrile qgserpltdt 301 eratlmdepy rkskltyaqa rkllgledta ffkglrygkd naeastlmem kayhaisral 361 ekeglkdkks plnlsselqd eigtafslfk tdeditgrlk drvqpeilea llkhisfdkf 421 vqislkalrr ivplmeqgkr ydeacaeiyg dhygkkntee kiylppipad eirnpvvlra 481 lsqarkving vvrrygspar ihietarevg ksfkdrkeie krqeenrkdr ekaaakfrey 25         541 fpnfvgepks kdilklrlye qqhgkclysg keinlvrlne kgyveidhal pfsrtwddsf 601 nnkvlvlgse nqnkgnqtpy eyfngkdnsr ewqefkarve tsrfprskkq rillqkfded 661 gfkecnlndt ryvnrflcqf vadhilltgk gkrrvfasng qitnllrgfw glrkvraend 721 rhhaldavvv acstvamqqk itrfvrykem nafdgktidk etgkvlhqkt hfpqpweffa 781 qevmirvfgk pdgkpefeea dtpeklrtll aeklssrpea vheyvtplfv srapnrkmsg 30         841 ahkdtlrsak rfvkhnekis vkrvwlteik ladlenmvny kngreielye alkarleayg 901 gnakqafdpk dnpfykkggq lvkavrvekt qesgvllnkk naytiadngd mvrvdvfckv 961 dkkgknqyfi vpiyawqvae nilpdidckg yriddsytfc fslhkydlia fqkdekskve 1021 fayyincdss ngrfylawhd kgskeqqfri stqnlvliqk yqvnelgkei rpcrlkkrpp 1081 vr 35          In some embodiments, dCas9 corresponds to, or comprises in part or in whole, a Cas9 amino acid sequence having one or more mutations that inactivate the Cas9 nuclease activity. For example, in some embodiments, a dCas9 domain comprises D10A and an H840A mutation or corresponding mutations in another Cas9. In some embodiments, the dCas9 comprises the amino acid sequence of dCas9 (D10A and H840A): 2020221355   24 Feb 2026 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI 5 QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT 10 NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL 15 QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDAIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS 20 DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD 25 (single underline: HNH domain; double underline: RuvC domain). In some embodiments, the Cas9 domain comprises a D10A mutation, while the residue at position 840 remains a histidine in the amino acid sequence provided above, or at corresponding positions in any of the amino acid sequences provided herein. In other embodiments, dCas9 variants having mutations other than D10A and H840A 30 are provided, which, e.g., result in nuclease inactivated Cas9 (dCas9). Such mutations, by way of example, include other amino acid substitutions at D10 and H840, or other substitutions within the nuclease domains of Cas9 (e.g., substitutions in the HNH nuclease subdomain and / or the RuvC1 subdomain). In some embodiments, variants or homologues of dCas9 are provided which are at least about 70% identical, at least about 80% identical, at 2020221355   24 Feb 2026 least about 90% identical, at least about 95% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical. In some embodiments, variants of dCas9 are provided having amino acid sequences which are shorter, or longer, by about 5 amino acids, by about 10 amino acids, by about 15 amino acids, 5 by about 20 amino acids, by about 25 amino acids, by about 30 amino acids, by about 40 amino acids, by about 50 amino acids, by about 75 amino acids, by about 100 amino acids or more. In some embodiments, Cas9 fusion proteins as provided herein comprise the full length amino acid sequence of a Cas9 protein, e.g., one of the Cas9 sequences provided 10 herein. In other embodiments, however, fusion proteins as provided herein do not comprise a full-length Cas9 sequence, but only one or more fragments thereof. Exemplary amino acid sequences of suitable Cas9 domains and Cas9 fragments are provided herein, and additional suitable sequences of Cas9 domains and fragments will be apparent to those of skill in the art. It should be appreciated that additional Cas9 proteins (e.g., a nuclease dead Cas9 15 (dCas9), a Cas9 nickase (nCas9), or a nuclease active Cas9), including variants and homologs thereof, are within the scope of this disclosure. Exemplary Cas9 proteins include, without limitation, those provided below. In some embodiments, the Cas9 protein is a nuclease dead Cas9 (dCas9). In some embodiments, the Cas9 protein is a Cas9 nickase (nCas9). In some embodiments, the Cas9 protein is a nuclease active Cas9. 20 Exemplary catalytically inactive Cas9 (dCas9): DKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATR LKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDE VAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQ LVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLT 25 PNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTE ITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFY KFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKD NREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTN FDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKV 30 TVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVL TLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFL KSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVD ELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ 2020221355   24 Feb 2026 NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDAIVPQSFLKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV GTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANG 5 EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSD KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL 10 GGD Exemplary catalytically Cas9 nickase (nCas9): DKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATR LKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDE 15 VAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQ LVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLT PNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTE ITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFY KFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKD 20 NREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTN FDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKV TVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVL TLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFL KSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVD 25 ELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV GTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANG 30 EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSD KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR 2020221355   24 Feb 2026 EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL GGD Exemplary catalytically active Cas9: 5 DKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATR LKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDE VAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQ LVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLT PNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTE 10 ITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFY KFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKD NREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTN FDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKV TVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVL 15 TLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFL KSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVD ELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV 20 AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV GTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANG EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSD KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH 25 YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL GGD. In some embodiments, Cas9 refers to a Cas9 from archaea (e.g. nanoarchaea), which constitute a domain and kingdom of single-celled prokaryotic microbes. In some 30 embodiments, Cas9 refers to CasX or CasY, which have been described in, for example, Burstein et al., "New CRISPR-Cas systems from uncultivated microbes." Cell Res. 2017 Feb 21. doi: 10.1038 / cr.2017.21, the entire contents of which is hereby incorporated by reference. Using genome-resolved metagenomics, a number of CRISPR-Cas systems were identified, including the first reported Cas9 in the archaeal domain of life. This divergent Cas9 protein 2020221355   24 Feb 2026 was found in little- studied nanoarchaea as part of an active CRISPR-Cas system. In bacteria, two previously unknown systems were discovered, CRISPR-CasX and CRISPR-CasY, which are among the most compact systems yet discovered. In some embodiments, Cas9 refers to CasX, or a variant of CasX. In some embodiments, Cas9 refers to a CasY, or a variant of 5 CasY. It should be appreciated that other RNA-guided DNA binding proteins may be used as a nucleic acid programmable DNA binding protein (napDNAbp), and are within the scope of this disclosure. In particular embodiments, napDNAbps useful in the methods of the disclosure include circular permutants, which are known in the art and described, for example, by Oakes 10   et al., Cell 176, 254-267, 2019. An exemplary circular permutant follows where the bold sequence indicates sequence derived from Cas9, the italics sequence denotes a linker sequence, and the underlined sequence denotes a bipartite nuclear localization sequence, CP5 (with MSP “NGC=Pam Variant with mutations Regular Cas9 likes NGG” PID=Protein Interacting Domain and “D10A” nickase): 15 EIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSM PQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFMQPTVAYSVLVVAKVEK GKSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRM LASAKFLQKGNELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISE FSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPRAFKYFDTTIARKEYR 20  STKEVLDATLIHQSITGLYETRIDLSQLGGDGGSGGSGGSGGSGGSGGSGGMDKKYSIGLAI GTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATRLKRTARRRYT RRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTI YHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFE ENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSNFDLA 25 EDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTEITKAPLSASM IKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKM DGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILT FRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKV LPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTVKQLKEDYF 30 KKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREM IEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRNF MQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHK PENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYLQ NGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKM 2020221355   24 Feb 2026 KNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNT KYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKKYPK LESEFVYGDYKVYDVRKMIAKSEQEGADKRTADGSEFESPKKKRKV* Non-limiting examples of a polynucleotide programmable nucleotide binding domain 5 which can be incorporated into a base editor include a CRISPR protein-derived domain, a restriction nuclease, a meganuclease, TAL nuclease (TALEN), and a zinc finger nuclease (ZFN). In some embodiments, the nucleic acid programmable DNA binding protein (napDNAbp) of any of the fusion proteins provided herein may be a CasX or CasY protein. 10 In some embodiments, the napDNAbp is a CasX protein. In some embodiments, the napDNAbp is a CasY protein. In some embodiments, the napDNAbp comprises an amino acid sequence that is 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 at ease 99.5% identical to a naturally-occurring CasX or CasY protein. In some embodiments, the 15 napDNAbp is a naturally-occurring CasX or CasY protein. In some embodiments, the napDNAbp comprises an amino acid sequence that is 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 at ease 99.5% identical to any CasX or CasY protein described herein. It should be appreciated that Cas12b / C2c1, CasX and CasY from other bacterial species may 20 also be used in accordance with the present disclosure. Cas12b / C2c1 (uniprot.org / uniprot / T0D7A2#2) sp|T0D7A2|C2C1_ALIAG CRISPR-associated endo- nuclease C2c1 OS = Alicyclobacillus acido- terrestris (strain ATCC 49025 / DSM 3922 / CIP 106132 / 25 NCIMB 13137 / GD3B) GN=c2c1 PE=1 SV=1 MAVKSIKVKLRLDDMPEIRAGLWKLHKEVNAGVRYYTEWLSLLRQENLYRRSPNGDGEQECD KTAEECKAELLERLRARQVENGHRGPAGSDDELLQLARQLYELLVPQAIGAKGDAQQIARKF LSPLADKDAVGGLGIAKAGNKPRWVRMREAGEPGWEEEKEKAETRKSADRTADVLRALADFG LKPLMRVYTDSEMSSVEWKPLRKGQAVRTWDRDMFQQAIERMMSWESWNQRVGQEYAKLVEQ 30 KNRFEQKNFVGQEHLVHLVNQLQQDMKEASPGLESKEQTAHYVTGRALRGSDKVFEKWGKLA PDAPFDLYDAEIKNVQRRNTRRFGSHDLFAKLAEPEYQALWREDASFLTRYAVYNSILRKLN HAKMFATFTLPDATAHPIWTRFDKLGGNLHQYTFLFNEFGERRHAIRFHKLLKVENGVAREV DDVTVPISMSEQLDNLLPRDPNEPIALYFRDYGAEQHFTGEFGGAKIQCRRDQLAHMHRRRG 2020221355   24 Feb 2026 ARDVYLNVSVRVQSQSEARGERRPPYAAVFRLVGDNHRAFVHFDKLSDYLAEHPDDGKLGSE GLLSGLRVMSVDLGLRTSASISVFRVARKDELKPNSKGRVPFFFPIKGNDNLVAVHERSQLL KLPGETESKDLRAIREERQRTLRQLRTQLAYLRLLVRCGSEDVGRRERSWAKLIEQPVDAAN HMTPDWREAFENELQKLKSLHGICSDKEWMDAVYESVRRVWRHMGKQVRDWRKDVRSGERPK 5 IRGYAKDVVGGNSIEQIEYLERQYKFLKSWSFFGKVSGQVIRAEKGSRFAITLREHIDHAKE DRLKKLADRIIMEALGYVYALDERGKGKWVAKYPPCQLILLEELSEYQFNNDRPPSENNQLM QWSHRGVFQELINQAQVHDLLVGTMYAAFSSRFDARTGAPGIRCRRVPARCTQEHNPEPFPW WLNKFVVEHTLDACPLRADDLIPTGEGEIFVSPFSAEEGDFHQIHADLNAAQNLQQRLWSDF DISQIRLRCDWGEVDGELVLIPRLTGKRTADSYSNKVFYTNTGVTYYERERGKKRRKVFAQE 10 KLSEEEAELLVEADEAREKSVVLMRDPSGIINRGNWTRQKEFWSMV NQRIEGYLVKQIRSR VPLQDSACENTGDI CasX (uniprot.org / uniprot / F0NN87; uniprot.org / uniprot / F0NH53) >tr|F0NN87|F0NN87_SULIH CRISPR-associated Casx protein OS = Sulfolobus 15 islandicus (strain HVE10 / 4) GN = SiH_0402 PE=4 SV=1 MEVPLYNIFGDNYIIQVATEAENSTIYNNKVEIDDEELRNVLNLAYKIAKNNEDAAAERRGK AKKKKGEEGETTTSNIILPLSGNDKNPWTETLKCYNFPTTVALSEVFKNFSQVKECEEVSAP SFVKPEFYEFGRSPGMVERTRRVKLEVEPHYLIIAAAGWVLTRLGKAKVSEGDYVGVNVFTP TRGILYSLIQNVNGIVPGIKPETAFGLWIARKVVSSVTNPNVSVVRIYTISDAVGQNPTTIN 20 GGFSIDLTKLLEKRYLLSERLEAIARNALSISSNMRERYIVLANYIYEYLTG SKRLEDLLY FANRDLIMNLNSDDGKVRDLKLISAYVNGELIRGEG >tr|F0NH53|F0NH53_SULIR CRISPR associated protein, Casx OS = Sulfolobus islandicus (strain REY15A) GN=SiRe_0771 PE=4 SV=1 25 MEVPLYNIFGDNYIIQVATEAENSTIYNNKVEIDDEELRNVLNLAYKIAKNNEDAAAERRGK AKKKKGEEGETTTSNIILPLSGNDKNPWTETLKCYNFPTTVALSEVFKNFSQVKECEEVSAP SFVKPEFYKFGRSPGMVERTRRVKLEVEPHYLIMAAAGWVLTRLGKAKVSEGDYVGVNVFTP TRGILYSLIQNVNGIVPGIKPETAFGLWIARKVVSSVTNPNVSVVSIYTISDAVGQNPTTIN GGFSIDLTKLLEKRDLLSERLEAIARNALSISSNMRERYIVLANYIYEYLTGSKRLEDLLYF 30 ANRDLIMNLNSDDGKVRDLKLISAYVNGELIRGEG Deltaproteobacteria CasX MEKRINKIRKKLSADNATKPVSRSGPMKTLLVRVMTDDLKKRLEKRRKKPEVMPQVISNNAA NNLRMLLDDYTKMKEAILQVYWQEFKDDHVGLMCKFAQPASKKIDQNKLKPEMDEKGNLTTA 2020221355   24 Feb 2026 GFACSQCGQPLFVYKLEQVSEKGKAYTNYFGRCNVAEHEKLILLAQLKPVKDSDEAVTYSLG KFGQRALDFYSIHVTKESTHPVKPLAQIAGNRYASGPVGKALSDACMGTIASFLSKYQDIII EHQKVVKGNQKRLESLRELAGKENLEYPSVTLPPQPHTKEGVDAYNEVIARVRMWVNLNLWQ KLKLSRDDAKPLLRLKGFPSFPVVERRENEVDWWNTINEVKKLIDAKRDMGRVFWSGVTAEK 5 RNTILEGYNYLPNENDHKKREGSLENPKKPAKRQFGDLLLYLEKKYAGDWGKVFDEAWERID KKIAGLTSHIEREEARNAEDAQSKAVLTDWLRAKASFVLERLKEMDEKEFYACEIQLQKWYG DLRGNPFAVEAENRVVDISGFSIGSDGHSIQYRNLLAWKYLENGKREFYLLMNYGKKGRIRF TDGTDIKKSGKWQGLLYGGGKAKVIDLTFDPDDEQLIILPLAFGTRQGREFIWNDLLSLETG LIKLANGRVIEKTIYNKKIGRDEPALFVALTFERREVVDPSNIKPVNLIGVARGENIPAVIA 10 LTDPEGCPLPEFKDSSGGPTDILRIGEGYKEKQRAIQAAKEVEQRRAGGYSRKFASKSRNLA DDMVRNSARDLFYHAVTHDAVLVFANLSRGFGRQGKRTFMTERQYTKMEDWLTAKLAYEGLT SKTYLSKTLAQYTSKTCSNCGFTITYADMDVMLVRLKKTSDGWATTLNNKELKAEYQITYYN RYKRQTVEKELSAELDRLSEESGNNDISKWTKGRRDEALFLLKKRFSHRPVQEQFVCLDCGH EVHAAEQAALNIARSWLFLNSNSTEFKSYKSGKQPFVGAWQAFYKRRLKEVWKPNA 15 CasY (ncbi.nlm.nih.gov / protein / APG80656.1) >APG80656.1 CRISPR-associated protein CasY [uncultured Parcubacteria group bacterium] MSKRHPRISGVKGYRLHAQRLEYTGKSGAMRTIKYPLYSSPSGGRTVPREIVSAINDDYVGL 20 YGLSNFDDLYNAEKRNEEKVYSVLDFWYDCVQYGAVFSYTAPGLLKNVAEVRGGSYELTKTL KGSHLYDELQIDKVIKFLNKKEISRANGSLDKLKKDIIDCFKAEYRERHKDQCNKLADDIKN AKKDAGASLGERQKKLFRDFFGISEQSENDKPSFTNPLNLTCCLLPFDTVNNNRNRGEVLFN KLKEYAQKLDKNEGSLEMWEYIGIGNSGTAFSNFLGEGFLGRLRENKITELKKAMMDITDAW RGQEQEEELEKRLRILAALTIKLREPKFDNHWGGYRSDINGKLSSWLQNYINQTVKIKEDLK 25 GHKKDLKKAKEMINRFGESDTKEEAVVSSLLESIEKIVPDDSADDEKPDIPAIAIYRRFLSD GRLTLNRFVQREDVQEALIKERLEAEKKKKPKKRKKKSDAEDEKETIDFKELFPHLAKPLKL VPNFYGDSKRELYKKYKNAAIYTDALWKAVEKIYKSAFSSSLKNSFFDTDFDKDFFIKRLQK IFSVYRRFNTDKWKPIVKNSFAPYCDIVSLAENEVLYKPKQSRSRKSAAIDKNRVRLPSTEN IAKAGIALARELSVAGFDWKDLLKKEEHEEYIDLIELHKTALALLLAVTETQLDISALDFVE 30 NGTVKDFMKTRDGNLVLEGRFLEMFSQSIVFSELRGLAGLMSRKEFITRSAIQTMNGKQAEL LYIPHEFQSAKITTPKEMSRAFLDLAPAEFATSLEPESLSEKSLLKLKQMRYYPHYFGYELT RTGQGIDGGVAENALRLEKSPVKKREIKCKQYKTLGRGQNKIVLYVRSSYYQTQFLEWFLHR PKNVQTDVAVSGSFLIDEKKVKTRWNYDALTVALEPVSGSERVFVSQPFTIFPEKSAEEEGQ RYLGIDIGEYGIAYTALEITGDSAKILDQNFISDPQLKTLREEVKGLKLDQRRGTFAMPSTK 2020221355   24 Feb 2026 IARIRESLVHSLRNRIHHLALKHKAKIVYELEVSRFEEGKQKIKKVYATLKKADVYSEIDAD KNLQTTVWGKLAVASEISASYTSQFCGACKKLWRAEMQVDETITTQELIGTVRVIKGGTLID AIKDFMRPPIFDENDTPFPKYRDFCDKHHISKKMRGNSCLFICPFCRANADADIQASQTIAL LRYVKEEKKVEDYFERFRKLKN IKVLGQMKKI 5           The term “Cas12” or “Cas12 domain” refers to an RNA guided nuclease comprising a Cas12 protein or a fragment thereof (e.g., a protein comprising an active, inactive, or partially active DNA cleavage domain of Cas12, and / or the gRNA binding domain of Cas12). Cas12 belongs to the class 2, Type V CRISPR / Cas system. A Cas12 nuclease is also referred to sometimes as a CRISPR (clustered regularly interspaced short palindromic repeat) 10 associated nuclease. The sequence of an exemplary Bacillus hisashii Cas 12b (BhCas12b) Cas 12 domain is provided below: MAPKKKRKVGIHGVPAAATRSFILKIEPNEEVKKGLWKTHEVLNHGIAYYMNILKLIRQEAI YEHHEQDPKNPKKVSKAEIQAELWDFVLKMQKCNSFTHEVDKDEVFNILRELYEELVPSSVE KKGEANQLSNKFLYPLVDPNSQSGKGTASSGRKPRWYNLKIAGDPSWEEEKKKWEEDKKKDP 15 LAKILGKLAEYGLIPLFIPYTDSNEPIVKEIKWMEKSRNQSVRRLDKDMFIQALERFLSWES WNLKVKEEYEKVEKEYKTLEERIKEDIQALKALEQYEKERQEQLLRDTLNTNEYRLSKRGLR GWREIIQKWLKMDENEPSEKYLEVFKDYQRKHPREAGDYSVYEFLSKKENHFIWRNHPEYPY LYATFCEIDKKKKDAKQQATFTLADPINHPLWVRFEERSGSNLNKYRILTEQLHTEKLKKKL TVQLDRLIYPTESGGWEEKGKVDIVLLPSRQFYNQIFLDIEEKGKHAFTYKDESIKFPLKGT 20 LGGARVQFDRDHLRRYPHKVESGNVGRIYFNMTVNIEPTESPVSKSLKIHRDDFPKVVNFKP KELTEWIKDSKGKKLKSGIESLEIGLRVMSIDLGQRQAAAASIFEVVDQKPDIEGKLFFPIK GTELYAVHRASFNIKLPGETLVKSREVLRKAREDNLKLMNQKLNFLRNVLHFQQFEDITERE KRVTKWISRQENSDVPLVYQDELIQIRELMYKPYKDWVAFLKQLHKRLEVEIGKEVKHWRKS LSDGRKGLYGISLKNIDEIDRTRKFLLRWSLRPTEPGEVRRLEPGQRFAIDQLNHLNALKED 25 RLKKMANTIIMHALGYCYDVRKKKWQAKNPACQIILFEDLSNYNPYEERSRFENSKLMKWSR REIPRQVALQGEIYGLQVGEVGAQFSSRFHAKTGSPGIRCSVVTKEKLQDNRFFKNLQREGR LTLDKIAVLKEGDLYPDKGGEKFISLSKDRKCVTTHADINAAQNLQKRFWTRTHGFYKVYCK AYQVDGQTVYIPESKDQKQKIIEEFGEGYFILKDGVYEWVNAGKLKIKKGSSKQSSSELVDS DILKDSFDLASELKGEKLMLYRDPSGNVFPSDKWMAAGVFFGKLERILISKLTNQYSISTIE 30 DDSSKQSMKRPAATKKAGQAKKKK. Amino acid sequences having at least 85% or greater identity to the BhCas12b amino acid sequence are also useful in the methods of the disclosure. The term “conservative amino acid substitution” or “conservative mutation” refers to the replacement of one amino acid by another amino acid with a common property. A 2020221355   24 Feb 2026 functional way to define common properties between individual amino acids is to analyze the normalized frequencies of amino acid changes between corresponding proteins of homologous organisms (Schulz, G. E. and Schirmer, R. H., Principles of Protein Structure, Springer-Verlag, New York (1979)). According to such analyses, groups of amino acids can 5 be defined where amino acids within a group exchange preferentially with each other, and therefore resemble each other most in their impact on the overall protein structure (Schulz, G. E. and Schirmer, R. H., supra). Non-limiting examples of conservative mutations include amino acid substitutions of amino acids, for example, lysine for arginine and vice versa such that a positive charge can be maintained; glutamic acid for aspartic acid and vice versa such 10 that a negative charge can be maintained; serine for threonine such that a free -OH can be maintained; and glutamine for asparagine such that a free -NH2 can be maintained. The term “coding sequence” or “protein coding sequence” as used interchangeably herein refers to a segment of a polynucleotide that codes for a protein. The region or sequence is bounded nearer the 5’ end by a start codon and nearer the 3’ end with a stop 15 codon. Coding sequences can also be referred to as open reading frames. The term “deaminase” or “deaminase domain,” as used herein, refers to a protein or enzyme that catalyzes a deamination reaction. In some embodiments, the deaminase is an adenosine deaminase, which catalyzes the hydrolytic deamination of adenine to hypoxanthine. In some embodiments, the deaminase is an adenosine deaminase, which 20 catalyzes the hydrolytic deamination of adenosine or adenine (A) to inosine (I). In some embodiments, the deaminase or deaminase domain is an adenosine deaminase catalyzing the hydrolytic deamination of adenosine or deoxyadenosine to inosine or deoxyinosine, respectively. In some embodiments, the adenosine deaminase catalyzes the hydrolytic deamination of adenosine in deoxyribonucleic acid (DNA). The adenosine deaminases (e.g., 25 engineered adenosine deaminases, evolved adenosine deaminases) provided herein can be from any organism, such as a bacterium. In some embodiments, the adenosine deaminase is from a bacterium, such as Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Shewanella putrefaciens, Haemophilus influenzae, or Caulobacter crescentus. In some embodiments, the adenosine deaminase is a TadA deaminase. In some 30 embodiments, the TadA deaminase is TadA variant. In some embodiments, the TadA variant is a TadA*8. In some embodiments, the deaminase or deaminase domain is a variant of a naturally occurring deaminase from an organism, such as a human, chimpanzee, gorilla, monkey, cow, dog, rat, or mouse. In some embodiments, the deaminase or deaminase 2020221355   24 Feb 2026 domain does not occur in nature. For example, in some embodiments, the deaminase or deaminase domain is 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 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%, at least 99.1%, 5 at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% identical to a naturally occurring deaminase. For example, deaminase domains are described in International PCT Application Nos. PCT / 2017 / 045381 (WO 2018 / 027078) and PCT / US2016 / 058344 (WO 2017 / 070632), each of which is incorporated herein by reference for its entirety. Also, see Komor, A.C., et al., 10 “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N.M., et al., “Programmable base editing of A»T to G«C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); Komor, A.C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 15   3:eaao4774 (2017) ), and Rees, H.A., et al., “Base editing: precision chemistry on the genome and transcriptome of living cells.” Nat Rev Genet. 2018 Dec;19(12):770-788. doi: 10.1038 / s41576-018-0059-1, the entire contents of which are hereby incorporated by reference. “Detect” refers to identifying the presence, absence or amount of the analyte to be 20 detected. In one embodiment, a sequence alteration in a polynucleotide or polypeptide is detected. In another embodiment, the presence of indels is detected. By "detectable label" is meant a composition that when linked to a molecule of interest renders the latter detectable, via spectroscopic, photochemical, biochemical, immunochemical, or chemical means. For example, useful labels include radioactive 25 isotopes, magnetic beads, metallic beads, colloidal particles, fluorescent dyes, electron-dense reagents, enzymes (for example, as commonly used in an ELISA), biotin, digoxigenin, or haptens. By “disease” is meant any condition or disorder that damages or interferes with the normal function of a cell, tissue, or organ. An example of a disease includes Glycogen 30 Storage Disease Type 1 (also known as GSD1 or Von Gierke Disease). In some embodiments, the GSD1 is Type 1a (GSD1a). By “effective amount” is meant the amount of a required to ameliorate the symptoms of a disease relative to an untreated patient. The effective amount of active 2020221355   24 Feb 2026 compound(s) used in accordance with the present disclosure for therapeutic treatment of a disease varies depending upon the manner of administration, the age, body weight, and general health of the subject. Ultimately, the attending physician or veterinarian will decide the appropriate amount and dosage regimen. Such amount is referred to as an “effective” 5 amount. In one embodiment, an effective amount is the amount of a base editor of the disclosure sufficient to introduce an alteration in a gene of interest (e.g., G6PC) in a cell (e.g., a cell in vitro or in vivo). In one embodiment, an effective amount is the amount of a base editor required to achieve a therapeutic effect (e.g., to reduce or control GSD1a or a symptom or condition thereof). Such therapeutic effect need not be sufficient to alter G6PC in all cells 10 of a subject, tissue or organ, but only to alter G6PC in about 1%, 5%, 10%, 25%, 50%, 75% or more of the cells present in a subject, tissue or organ. In one embodiment, an effective amount is sufficient to ameliorate one or more symptoms of GSD1a. By "fragment" is meant a portion of a polypeptide or nucleic acid molecule. This portion contains, at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the 15 entire length of the reference nucleic acid molecule or polypeptide. A fragment may contain 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 nucleotides or amino acids. By “glucose-6-phosphatase (G6PC) polypeptide” is meant a polypeptide or fragment thereof having at least about 95% amino acid sequence identity to NCBI Accession No. 20   AAA16222.1. In particular embodiments, the disclosure provides a method of editing a G6PC polynucleotide comprising a single nucleotide polymorphism (SNP) associated with Glycogen Storage Disease Type 1a (GSDla). In one embodiment, the A»T to G»C alteration at the SNP associated with GSD1a changes a glutamine (Q) to a non-glutamine (X) amino acid in the G6PC polypeptide. In another embodiment, the A«T to G^C alteration at the SNP 25 associated with GSD1a changes an arginine (R) to a non-arginine (X) in the G6PC polypeptide. In one embodiment, the SNP associated with GSD1a results in expression of an G6PC polypeptide having a non-glutamine (X) amino acid at position 347 or a non-arginine (X) amino acid at position 83. In one embodiment, the base editor correction replaces the glutamine at position 347 with a non-glutamine amino acid (X). In another embodiment, the 30 base editor correction replaces the arginine at position 83 with a non-arginine amino acid (X). In particular embodiments, G6PC comprises one or more alterations relative to the following reference sequence. In particular embodiments, G6PC associated with GSD1a comprises one 2020221355   24 Feb 2026 or more mutations selected from Q347X and R83C. An exemplary G6PC amino acid sequence from Homo Sapiens is provided below: 1     MEEGMNVLHD FGIQSTHYLQ VNYQDSQDWF ILVSVIADLR NAFYVLFPIW FHLQEAVGIK 61    LLWVAVIGDW LNLVFKWILF GQRPYWWVLD TDYYSNTSVP LIKQFPVTCE TGPGSPSGHA 5   121   MGTAGVYYVM VTSTLSIFQG KIKPTYRFRC LNVILWLGFW AVQLNVCLSR IYLAAHFPHQ 181   VVAGVLSGIA VAETFSHIHS IYNASLKKYF LITFFLFSFA IGFYLLLKGL GVDLLWTLEK 241   AQRWCEQPEW VHIDTTPFAS LLKNLGTLFG LGLALNSSMY RESCKGKLSK WLPFRLSSIV 301   ASLVLLHVFD SLKPPSQVEL VFYVLSFCKS AVVPLASVSV IPYCLAQVLG QPHKKSL By “glucose-6-phosphatase polynucleotide” is meant a polynucleotide encoding a 10 G6PC polypeptide. An exemplary G6PC nucleotide sequence from Homo Sapiens is provided below (GenBank: U01120.1): 1 ATAGCAGAGC AATCACCACC AAGCCTGGAA TAACTGCAAG GGCTCTGCTG ACATCTTCCT 61 GAGGTGCCAA GGAAATGAGG ATGGAGGAAG GAATGAATGT TCTCCATGAC TTTGGGATCC 121 AGTCAACACA TTACCTCCAG GTGAATTACC AAGACTCCCA GGACTGGTTC ATCTTGGTGT 15   181 CCGTGATCGC AGACCTCAGG AATGCCTTCT ACGTCCTCTT CCCCATCTGG TTCCATCTTC 241 AGGAAGCTGT GGGCATTAAA CTCCTTTGGG TAGCTGTGAT TGGAGACTGG CTCAACCTCG 301 TCTTTAAGTG GTAAGAACCA TATAGAGAGG AGATCAGCAA GAAAAGAGGC TGGCATTCGC 361 TCTCGCAATG TCTGTCCATC AGAAGTTGCT TTCCCCAGGC TATTCAGGAA GCCACGGGCT 421 ACTCATGCTT CCAACCCCTC TCTCTGACTT TGGATCATCT ACATAAAGGG GGAAGACAGA 20   481 AAAAATCCTA CCAGTGAGTT GAAAATACAG GAAAGCCTAT TTCATATGGG TTAAAGGGTA 541 GGACAGTTGA ATTTCGTGAA AAGTCTGAGT TATATAGGCT TTGAGCAAAG AGTTTTATTA 601 GTATGAAGCA GAAGAGGTAA CATAAAGAAA GATGTATGGG GCCAGGCATG GTGGCTCACA 661 CCTGTAATCC CAGCACTTTG GGAGGCCGAG GTGGGCGAAT CACTCCTGGG TGAACTCAGG 721 AGTTCAAGAC CAGCCTGGGC AACATGGCGA AACTCCATCT CTACAAAAAC ATTACGAAAA 25   781 TTAGCTGGGC GTGTTGGTGC TGTAGTCCCA GCTACTCAGG AGGCTGAGGT GAGAGGCGGA 841 GGAGGTTGCA GTGAGTCAAG ATCATGCCAC TGCACTCCAG CCTGGGCAAC AGAGTAAGAC 901 CCTGTCTCAA AAAAAAAAAA AAGATAGATG ATGTATGCTG TATGAAAAAA GGAAACACAC 961 AGATGATTCA ACAGCCTGTT TTGTGGGGTA ATGAAAAGTC ACCCTGGGAA CTGGGCTCCA 1021 GCCCTCGTTC TGCCACCCAC CAACTACATG TCCTTGGCAA GTCATATCAA TTATCTGAGT 30   1081 TTCTGTTTTA TAATCTACAA ATAGGTTATC TCTGGCAGCT TAATAATAAT CAGGGTTAAC 1141 ATTTATTAAA CAGTGTGTGC CAGTCCATGT GCTATGTGCT TTTCTGTGAG GTAGTTACTG 1201 CTATTTACAG AAACAGTAGA TGCAGAGACC AAGGTGCTGA GTTAAATGAT TAGGCCAACA 1261 AGGTTAGTAC ATGCCGAGCC AGGATGGAAG CCCAGGTAGG CAGGCTGGCT TCCGCGGCAA 1321 TGCTCTTATG AACTATGTTA CGTCCAGTGC TGATAAACTG ACTCTCTGGG GAGCAGGGGA 35   1381 AAGCCCTGAG TTTAGCATTT GCCAATTTCT ATCACGTAAA CATTCCCATT CTGGCCACTT 1441 TCTTTCTTTC TTTCTTTTGT TTGTTTGTTT GAGATGGAGT CTCGCACTGT TGCCTGGCTG 1501 GAGTGCAATG GTGCAATCTC AGCTCACTGC AACCTCTGCC TCTCCGGTTC AAGTGATTCT 1561 CCTGCCTCAG CCTCCCAAGT AGCTGGGATT ACAGGTGCCC GCCACCATGC CCAGCTAATT 1621 TTTTTTGTAT TTTTAGTAGA GACATGGTTT CACTATGTTG ACTAGGCTGG TCTCGAACTC 2020221355   24 Feb 2026 1681 CTGACCTCAT GATCTGCCTG CCTTGGCCTC CCTAAGTGCT AGGATTACAG GCGTGAGCCA 1741 CTACACCCAG CCGCATGATT CTAAAAAATA AAAAGATGAA GTGTTATTCC AAACATCTGA 1801 TCTCCATTGA AGAACCATGC AATCTCTCTG GGTTGATAGA GGCCAGAGTT AGTGGCTCTC 1861 CCTGATTTCG GTGAGAAATC ACTATTCCAC CATCACGGGA TAAAAGGCAT CCTGACTGGC 5   1921 GGTTGACACC TATTTCCACA GTGAAAGATA TATCTAGTAC TTTTAAAGGG GAAGTGGTTT 1981 GTCTGAGATA CTCTGTTTCA AAGTAGAGAG GATACAGAAC AAGCATCTGA AGCTATATAC 2041 ATCCTTACAG AGAGCAATTC TGATGGAAAT GCAGGCCATG TTTCCCTGGG GGGGGCTCGT 2101 CCTAGGGGCT GGAGTGCATT CTCTGATGTC AGAGGAAATG CAAGATTCCC TGAGGCCTGA 2161 GGGAACCCAT GGTATATGCA AGTCCAAGTT TCAAACTGTA GTTCCATATG CATTCTTCCA 10   2221 GGACAAATAC TTCTTGAGGT TAAAAAAAAA AAGTCACATA GCTGCCATTT TATGGATTTC 2281 AGGATTTTTT TTTTTTTTTT TTTGAGATGG AGTCTTGCTC TGTCACCCAG CCTGTAGTGC 2341 AGTGGCATAA TCTCGGCTCA CGGCAACCTC CGCCTCCCAG GTTCAAGCGA TTCTCTTGCC 2401 TTAGCCTCCC GAGTAGCTGG GATTACAGTC ACGCACCACC ACATCTGGCT AATTCTTTAT 2461 ATTTTTTGGT AGAAACGGTG TTTCACCATG TTGGCCAGGC TGGTCTCAAA CTCCTGACCT 15   2521 CATGTGATCT GCCTGCCTTG GCCTCCCAAA GTGCTGAGAT TACAGGTGTG AGCCACCGCG 2581 CCTGCCTGGA GTTCAGAATC TTGGGCTTCA TTATTTGTGT TTAAATAGAT CATACAGTCA 2641 GGCACGGTGG CTCATGCCTG TAATCCCAGC ACTTTGGGAG GCTGAGGTGG GAGGATTGCC 2701 TGAGTTCAGG AGATGGAGAC CAGCCTGGGC AACATGGTGA AACCCCGTCT CTACTAAAAA 2761 TACAAAAACT AGCTGGATGT GGTGGCACAC ACCTGTAGTC CCAGCTATTC AGGAGGCTGA 20   2821 GGTGGGAGGA TCCCAGGAGG TAGAGGTCAC AATGAGCCGA GATTGCGCCA CTGCACTCCA 2881 GGCTGGGTTA CTGAGCCAGA TCCTGTCTCA AAAAAAAAAA AGATAATACA TTCAAACAGT 2941 TCAAAATGCA AAAGTTACAT ACATAAGGAA GTGTCATGAA ATATCTCCCT CTCACACTTC 3001 TCCCCAGCCA CCCAGTTCTC CCTTCTAGAG GCAACATGTG AAATCCTTCT CAGGCTACAC 3061 TCTTCTTGAA GGTGTAGGCT TTGGGCAAAA GCATTCATTC AGTAACCCCA GAAACTTGTT 25   3121 CTGTTTTTCC ATAGGATTCT CTTTGGACAG CGTCCATACT GGTGGGTTTT GGATACTGAC 3181 TACTACAGCA ACACTTCCGT GCCCCTGATA AAGCAGTTCC CTGTAACCTG TGAGACTGGA 3241 CCAGGTAAGC GTCCCAGCCC CTGCAGACAG AAGCTGAGTG GACCTCGTTT ACCTGTTATG 3301 GATGAAACTG ACCTTGAGGG GACATGAGGA GAGCCATTCC TTTGTACTTT TGTCATGCTC 3361 TTCAATTGGC ACAAATTAAT TCACTTCTGC AATACTTTCC TGAATAGCAC AGTAGTATTG 30   3421 GAAATCTGCC TATTACAGAA CCTGGATGGA GTCCAGAGAG GCACGGGCAT CCATGGGCAA 3481 AGGGCTCGTG AGAGTCACCG CCCTGCAGCG CTGTGTCCTG AGAAAGGAGG GGGCAGAAGC 3541 CTGAGCTTCT GGGGGTCCTT CCCAATGGCC TGGCCCACTG GATGTGCCCT CCTGAGCTGA 3601 CCGTCCAATC CCTTGCCCTC TCTGTGCCTA CGTTTTATTA GTTACAGCCA GATGGTTACT 3661 GTCAAATCAA ATGATAGATT TCATTTTCAG TATGTAATAG GAAGCCCCTC CCTCACCCTA 35   3721 AAGTCTCAGC TGCCCTCTAA GACTAGTACT CTCTAAGGTA CTAGTATCCC TTCCTCAGAG 3781 ACCCTTTCCC TGACCCCAAA ACTAGGGAAG GTCCCTTAGT TATTTGCTCT CACAGACCAC 3841 GCATTTACCT CAGAGCATAT TCACTCATTC AGCTGTTACT TACCAAGCAC CTACTGGGAG 3901 CTATACACTG TTCTATGTGC TAGGGATACC TCTGTCAGTG AACAACACAG ACACAAAGAT 3961 CCCTGCCCTT GTGGAGCTGA AATCTGAATA GAGGAGGTGA AATATACAAA AATTATAATA 40   4021 AATAAGTAAA CTAGGCCAGT TGTGGTTGCT CATGCCTGTA ATCCCAGCAC TTTGGGAAGC 4081 CAAGGTAGGT AGATCACCTG AGGTCAGGAG TTCAAAACCA GCCTGGCCAA CATTGCAAAA 2020221355   24 Feb 2026 4141 TCCTGTCTTT ACTAAAAATG GAAAAATTGG TCAGGCGTGA TGGCACACGC CTGTAGTCTC 4201 AGCTACCTGG GAGGCTGAGG CAGGAGAATC GCTTGAACCT GGGAGGCAGA GGTTGCAGTG 4261 AACCGAGATC GGACCACTGC ACTCCAGCCT GAATGACAGA ACGAGACTCT GTCTCAAAAA 4321 AAAAGTAAAC TATTAATATG TAGGATAGGC CAGGCACGGT GGCTCACCCT GTAATCCCAG 5   4381 CACTTTGGGA GGCTGAGGCG GGTGGATCAC CTGAGGTGAG GAGTTCAAGA CCAGCCTGGC 4441 CAACATGGCA AAACCCTGTC TCTACTAAAA ATACAAAAAT TAGCTGGGTG TCCTGGTGCA 4501 TGCCTGTAAT CTGAGCTACT CAGGAGGCTA AGGCAGGAGA ATCGCTTGAA CCTGGGAGGT 4561 GGTGAGCCAA GATTGCGCCA TTGCACTCCA GCCTGGGCGA CAAAATGAGA CACCATCTGA 4621 AAAAAAAAAA AAAATATATA TATATATACA CACACACACA CACACACACA CACACACACA 10   4681 TATAATACTA GAAAATGATT GTTTATAGGC AAAAAAAAAA AAAAAGAAGA AGAAGAAGAA 4741 AAGGAAAGGA GAAGGAAAGA AGGACCAAAC ATCTTTTGTA GAAATATGTT TGCTTTCATC 4801 ATAACAGCTT GTTATCAAGG ATGAATTTCT CCCTGAAATT AATGGAGGCA CAGACTGGAA 4861 AGTTTAAAGT GGCTTTAAGA GGTTATTTTA TTTAGTCCTC TGTCTTAATA GAAGCAAATT 4921 ATTATCTCTG CTCCTTAGGT AGAGTAGCTA AGGCTCAGAA AGTAGGCCGG GCGCGGTGGC 15   4981 TCACGCCTGT AATCCTAGCA CTTTGGGAGG CCAACGCAGG TGGATCACCT GAGGTCAGGA 5041 GTTTGAGACC AGCCTGGCCA ACATGGTGAA ACCTCGTCAC TAATAAAAAA ATACAAAAAC 5101 TTAGCCAGGC ATGGTGGCGG GCGCCTGTAA TCCCAGCTAC CCAGGAGGCT GCGGCAGGAG 5161 AATCACTTCA ACCCGGGAGG CAGAGGTTGC AGTGAGCTGA AATCACACCA CTGCACTCCA 5221 GCCTTGGTGA CAGAGAAAGA TTCTGTCAGG AAAAAAAAAA AAAAGTTTAA ATGAATTACC 20   5281 CAAGGTATAT AATTGTTAGT GTTAGAAGGA AGAAGAAGGG AGGGAGGAAG GAAGGGAGAA 5341 AGAAAGGGAA GGAGGAAGGG AGGGAGGGAA GAAAGCCTTT ATTTATCTAT GGGGTTCCCT 5401 GGAAAGCAGG CTGAAATGGA GATTCACGTG CAGGAGTTTA GATACTCTGG GGAACTATAC 5461 TTGTAGAAGG GAAGGAACAG GAACAGGGCA GAAGGAGAGG TCCGGTTGTG ATTCTGCCTC 5521 ATCCAACCCC ACAGCGAGCT CTGAAGCTGG GGATGGCTCC TCAGAGTTGG TCCAAGTTGG 25   5581 GACAAGGGAA TCAGACCCTG GGGAGAGCGT AACCTTGATC AAGGCGACTC TCTTTAGCCC 5641 AGGGCAATGC CAGGAGAAGG CTGAGAGCAG AAAGCCATCT ACCATCACAC TCTCAACAGC 5701 TACGAAATAA GTCCTGCAGT TCAGGAGGGA GGTCTGGGCG GCACATCTCA GGACCCTCTA 5761 TCTCTCAGGG TAGAGGAATT AAGAATGGGA TGGGAACCAG ACGGGCCATG GTGGCTCACA 5821 CCTATAATCC CAACACTTTG GGAGGCCAAG GGTAGGAGGA TTGCTTGAGC CCAAGAGTTC 30   5881 AAAACCAGCC TGGGCAAAAA CAATCAAACA AACAAACAAA ACACATTTAA AAAATTTGCT 5941 GTGTGTGGTG GTGTGCACCT GTGGTCCCAG CTACTCAGGG GGCTGAGGTG GGAGGATTGC 6001 TTGAGTCCAG GAGGTCGAGG CTGCAGTGAG CTATGATCAT GGCACTGCAT TGCAGCCTAG 6061 GAGACAAAGC AAGACACTGT CTCTAAAAAA ACAAAAAACA AACAAATAAA AAAACGGAAC 6121 CGGTTGCAAG CAGGGTTAAA TAGCGTGGTC AGAGTAGGAC TCACTGAGAA TATGAGATCT 35   6181 GAGTCAAGTC TTCAAGGATG TGAGGAAGTA AGTTTCTGGC AGAAGAGCTG TGAAGGGCTG 6241 TCTGGCCAGA GAAGATTGCA ATGCAAAAGC CCTGAGGTGG GAACGTGTTT GGTGTGTTTA 6301 AAGGAAAGCA ATGAGGCCAG TGTAGCCAGA ACAGAGTGTG CAAGGAGAGA AGGAACAGAA 6361 GATGTGGAGG GCAGATCAGT TTGTAATTGT ACGCCCAGTA TGCTGATTCT TTGTGTAATC 6421 TCCAGACTGT ATTAAACTGC AAGAGCAGGG CCCCTCTCTG GCTTTGCTCA TCATTGTATT 40   6481 CCCAGAGCCT TGCACAATGC TTGGTGCATA GGAGATGGAA ATTTGTTAAA TAAATGAATT 6541 ATGGATAACG AATGGATGGT AAGATGGGTG GATGGATGGG GGGTGAACGG ATGGATGGGG 2020221355   24 Feb 2026 6601 GGTGAATGGA TGGATGAATG GGTAGATGGG TGGATAGGGG GATGGCTGGG TGGCTGGGTA 6661 GATGATGCAC TGTCTCCCAG ATGAGGACCT TTTCACCTTT ACTCCATTCT CTTTCCTGCC 6721 CTTTAGGGAG CCCCTCTGGC CATGCCATGG GCACAGCAGG TGTATACTAC GTGATGGTCA 6781 CATCTACTCT TTCCATCTTT CAGGGAAAGA TAAAGCCGAC CTACAGATTT CGGTAAGAAC 5   6841 TCACCACTGG GGTGTAGGTG GTGGAGGGCA GGAGGCAGCT CTCTCTGTAG CTGACACACC 6901 ACGTATTCTT CCTCACATCC CCCTAGCCCG CTCCCACACC TGGGCAGCCG CTGATTAAGA 6961 GTTGTGGCAC TTTGGATAGG GATAAACCTC AGAGTCAGGG AATGTTTGGG CTGAAAGGGA 7021 TCCAGTAGTG CAATCCGTTG TTTTACAGAT AAGGAAACAA AGCCCAACAC CATGAAGGGA 7081 CTTATAAAAA TAAGGTAGTG AAGTAGCAGC AGGGCTTAAA TAAAAACCCA TGTCTGTACC 10   7141 AACCACAGAG TCACCCATCC AGGTTAAAAT AACCAGAGAA ACAGAAGATA TTCCTACTAC 7201 AGAGAATTCC GGGTGTGCAG CCACAGTGCA AATCCTTTTT ATTTTTATTT TTGAGATGCA 7261 GTCTCGCTCT GTCATCCAGG CTGAAGTGCA GTGGCACGAT CATGTCTCGC TGCAACCTCT 7321 GCCTCCCAGG CTCAAGCGAT CCTCCCACCT CAGCCATCTG AGTAGCTGGG ACCACAGGCC 7381 ACACACCACA CCCAGCTAAT TTCTCGTATC TTTTTGTAGA GACAGAGTTC TGCTATGTTG 15   7441 CCCAGGCTCA GGCTGGTCTT GATCTCAAGC AATTGGCTTG CCTCAGCCTC CTAAAATATT 7501 GGGATTACAG GCATGAGCCA CCGCGCCAGC CATGCAAATC CTTAATTATC AAACAGATAA 7561 AATAGGGAAG TTAAAATTCA TATACACAAG GGTTAACCAC TTGCCACAGG CATTTTTTTT 7621 TTTTTTTTGA GACGGAATCT CGCTCTGTTG CCCAGGCTGG AGTGCAGTGG CGCCATCTCG 7681 CCTCACTGCA ACCTCCGCTT CCTGGGTTCA AGCTATTCTT CTGCCTCAGC CTACCGAGTA 20   7741 GCTGGGACTA CAGGCACGTG CCACCACACC TGGCTAATTT TTTTATTTTT AGTAGAGATG 7801 GGGTTTCACC ATATTGGCCA GGCTGGTCTT GAACTCCTGA CCTAGTGATC CATCCGCCTC 7861 AGCCTCCCAA AGTGCTGGGA TTGCAGGCAT GAGCCACCGC GCCTGGCCTT TTTTTTTTTT 7921 TTTTGAGACG GAGTTTTGCT CTTGTTGCCC AGGCTAGAGT GCAGTGGCGC AGTCTCGGCT 7981 CACTGTAACC TCCACCTCCT GAGTTCAAGC AATTCTCCTG CCTCAGCCTC TCAAATAGCT 25   8041 GGGATTACAG GCGTGAGCCA CCCCACCTGG CTAATTTTGT AATTTTTTTT TTAGTAGAGA 8101 TGGGGTTTCA CCTGTTGATC AGGCTGGTCT CAAACTCCTG ACCTCAAGTG ATCCACCCAC 8161 CTCGGCCTCC CAAAGTGCTG GGATTACAAG CATAAGCCAC CGTGCCTGGT CAATTTTGAT 8221 CTTTTTTAAA GAGACAGGGG TCTTGCTATG TTGCCCAGAC TAGTCTTGAA CTCCTGGCCT 8281 CAAGTGATCC TCTCACCTCG GCCTCCCAAA GTATTGGGAT TACAGGTCTG AGCCGCTGCA 30   8341 CCCAGCCCCC AACAGGCATC TTTGGACTTT TGAGTACTGG CTTTAATTTA CAAAAATTCC 8401 ACTGAGAGCA CCTAAGTTTG CCAGGCTCCA ACATTTCTGC AGGGGCTGTT TTCTTTGCTG 8461 AAGGATCTGC ACCTGTGTTC TGTTATGGTT GCCTCTTCTG TTGCAGGTGC TTGAATGTCA 8521 TTTTGTGGTT GGGATTCTGG GCTGTGCAGC TGAATGTCTG TCTGTCACGA ATCTACCTTG 8581 CTGCTCATTT TCCTCATCAA GTTGTTGCTG GAGTCCTGTC AGGTATGGGC TGATCTGACT 35   8641 CCCTTCCTTC TCCCCCAAAC CCCATTCCGT TTCTCTCCCT AATCAGGACA AAATCCCAGC 8701 ATTCCAGCCA CATCCTGTGT GTAATCAGTA CTGTTAGCAT TTCTGTGGGT TGAAAGTCAA 8761 GAATGAGCAA CTTGAAATGA TTAATTTCTA TAAGAGTGCC CAGATCTATA GAATGAATTG 8821 TGTAGAAGTT ACCATACATC AAATTAACGC ACCAAATTGA ATTAGCTTGA AATCTCAGAG 8881 CTTTTTACAA TCTTTATTTC TTACTGGTCT TCAACAGGCC CTAATTTACT TTTCAGGGAA 40   8941 TCTGCCAAAT TTAACAAATT AACACGATGT CCTAGGAAAG CTGTTCATTT AAATACATTC 9001 ATTTGCAAAC CTAATAGATA ACTGCAGTTG ATCTCTTTTA TAGGTTCAGA GTTTTGAATA 2020221355   24 Feb 2026 9061 TGTTTTTTTT TGTTTTTTTT TTTTGAGATG GAGTCTCGCT CTGTGACCCA GGCTAGAGTG 9121 CAGTGGTGCG ATCTCGGCTC ACTGCAAGCT CCACCTCCTG GGTTCACGCC ATTCTCCTGC 9181 CTCAGCCTCT CCGAGTAGCT GGGACTACAG GCGCCCGCCA CCATGCCCGG CTAATTTTTT 9241 GTATTTTTAG CAGAGACGGG GTTTCACCGT GGTCTTGATC TCCTGACCTC GTGATCCGCC 5   9301 CGCCTCGGCC TCCCAAAGCG CTGGGATTAC AAGGGTGAGC CACCGCACCC TGCCTGAATA 9361 TGTGTTTTCT TAGATCCAAT TAACAAGGGT AAGACAAGAT TTAAGTTAAG CATAAGAAAG 9421 ATTTTGTGGG AGGCACTGGA ATATAAGACC TTAACAAAAC TGTGGAATTT CTCCCCTGGA 9481 GATTTGTAAG AACGGAACAT AGCAGCATTC AAAGAAGAAT GTTGAGAACA AGGGAGATAA 9541 TGGTTTCATG GTAATCACAA AAGTAACACA GCATTTAGTA CTGGGTTCCA TGTTTGAGGA 10   9601 AGAACCTGGA AGCCATATCA CATGAAAAAC CTGGGAATGT TTAGGTTAGA GAGAATAACT 9661 GTGTTCAAAT GTGTGACAGA GGGACTAGAT TCATCACTTA CTAACTCCTG CAGAAAGAAC 9721 TGAGAAAAAT AGACAGTATT AGAGGGGGAC CAGTTTCACA CAGACAAGGA AGAACTATTC 9781 AGCAATCAAT TCCGTTCAAA GATAAAATGG ACTGTTATAG TGGGGGTGAG CTCCCTACCT 9841 CTGAGGGTAT TTCAAGTAGA GATAGGAGGA CCTCCTGGTA GGAAATTTGC ATACGGTGGG 15   9901 AGATTGTACG TGATATGGCA CCTCCATCTG AAAGAGTCTA TATTGAGGGC AGGCTGGAGT 9961 CACACATGGG AATAAGCCAG GCGACCCTCC CATCTGCCAT CTGTGATTTA ATTCCACAGT 10021 CGCAGAACGG ATGGCATGTC ACCCACTCCT CCAAACCCAC CTCTAGCAAA GGTCCCAAAT 10081 CCTTCCTATC TCTCACAGTC ATGCTTTCTT CCACTCAGGC ATTGCTGTTA CAGAAACTTT 10141 CAGCCACATC CACAGCATCT ATAATGCCAG CCTCAAGAAA TATTTTCTCA TTACCTTCTT 20   10201 CCTGTTCAGC TTCGCCATCG GATTTTATCT GCTGCTCAAG GGACTGGGTG TAGACCTCCT 10261 GTGGACTCTG GAGAAAGCCC AGAGGTGGTG CGAGCAGCCA GAATGGGTCC ACATTGACAC 10321 CACACCCTTT GCCAGCCTCC TCAAGAACCT GGGCACGCTC TTTGGCCTGG GGCTGGCTCT 10381 CAACTCCAGC ATGTACAGGG AGAGCTGCAA GGGGAAACTC AGCAAGTGGC TCCCATTCCG 10441 CCTCAGCTCT ATTGTAGCCT CCCTCGTCCT CCTGCACGTC TTTGACTCCT TGAAACCCCC 25   10501 ATCCCAAGTC GAGCTGGTCT TCTACGTCTT GTCCTTCTGC AAGAGTGCGG TAGTGCCCCT 10561 GGCATCCGTC AGTGTCATCC CCTACTGCCT CGCCCAGGTC CTGGGCCAGC CGCACAAGAA 10621 GTCGTTGTAA GAGATGTGGA GTCTTCGGTG TTTAAAGTCA ACAACCATGC CAGGGATTGA 10681 GGAGGACTAC TATTTGAAGC AATGGGCACT GGTATTTGGA GCAAGTGACA TGCCATCCAT 10741 TCTGCCGTCG TGGAATTAAA TCACGGATGG CAGATTGGAG GGTCGCCTGG CTTATTCCCA 30   10801 TGTGTGACTC CAGCCTGCCC TCAGCACAGA CTCTTTCAGA TGGAGGTGCC ATATCACGTA 10861 CACCATATGC AAGTTTCCCG CCAGGAGGTC CTCCTCTCTC TACTTGAATA CTCTCACAAG 10921 TAGGGAGCTC ACTCCCACTG GAACAGCCCA TTTTATCTTT GAATGGTCTT CTGCCAGCCC 10981 ATTTTGAGGC CAGAGGTGCT GTCAGCTCAG GTGGTCCTCT TTTACAATCC TAATCATATT 11041 GGGTAATGTT TTTGAAAAGC TAATGAAGCT ATTGAGAAAG ACCTGTTGCT AGAAGTTGGG 35   11101 TTGTTCTGGA TTTTCCCCTG AAGACTTACT TATTCTTCCG TCACATATAC AAAAGCAAGA 11161 CTTCCAGGTA GGGCCAGCTC ACAAGCCCAG GCTGGAGATC CTAACTGAGA ATTTTCTACC 11221 TGTGTTCATT CTTACCGAGA AAAGGAGAAA GGAGCTCTGA ATCTGATAGG AAAAGAAGGC 11281 TGCCTAAGGA GGAGTTTTTA GTATGTGGCG TATCATGCAA GTGCTATGCC AAGCCATGTC 11341 TAAATGGCTT TAATTATATA GTAATGCACT CTCAGTAATG GGGGACCAGC TTAAGTATAA 40   11401 TTAATAGATG GTTAGTGGGG TAATTCTGCT TCTAGTATTT TTTTTACTGT GCATACATGT 11461 TCATCGTATT TCCTTGGATT TCTGAATGGC TGCAGTGACC CAGATATTGC ACTAGGTCAA 2020221355   24 Feb 2026 11521 AACATTCAGG TATAGCTGAC ATCTCCTCTA TCACATTACA TCATCCTCCT TATAAGCCCA 11581 GCTCTGCTTT TTCCAGATTC TTCCACTGGC TCCACATCCA CCCCACTGGA TCTTCAGAAG 11641 GCTAGAGGGC GACTCTGGTG GTGCTTTTGT ATGTTTCAAT TAGGCTCTGA AATCTTGGGC 11701 AAAATGACAA GGGGAGGGCC AGGATTCCTC TCTCAGGTCA CTCCAGTGTT ACTTTTAATT 5   11761 CCTAGAGGGT AAATATGACT CCTTTCTCTA TCCCAAGCCA ACCAAGAGCA CATTCTTAAA 11821 GGAAAAGTCA ACATCTTCTC TCTTTTTTTT TTTTTTTGAG ACAGGGTCTC ACTATGTTGC 11881 CCAGGCTGCT CTTGAATTCC TGGGCTCAAG CAGTCCTCCC ACCCTACCAC AGCGTCCCGC 11941 GTAGCTGGGA CTACAGGTGC AAGCCACTAT GTCCAGCTAG CCAACTCCTC CTTGCCTGCT 12001 TTTCTTTTTT TTTCTTTTTT TGAGACGGCG CACCTATCAC CCAGGCTGGA GTGGAGTGGC 10   12061 ACGATCTTGG CTCACTGCAA CCTCTTCCTC CTGGTTCAAG CGATTCTCAT GTCTCAGCCT 12121 CCTCAGTAGC TAGGACTACC GGCGTGCACC ACCATGCCAG GCTAATTTTT ATATTTTTAG 12181 AATTTTAGAA GAGATGGGAT TTCATCATGT TGGCCAGGCT GGTCTCGAAC TCCTGACCTC 12241 AAGTGATCCA CCTGCCTTGG CCTCCCAAGG TGCTAGGATT ACAGGCATGA GCCACCGCAC 12301 CGGGCCCTCC TTGCCTGTTT TTCAATCTCA TCTGATATGC AGAGTATTTC TGCCCCACCC 15   12361 ACCTACCCCC CAAAAAAAGC TGAAGCCTAT TTATTTGAAA GTCCTTGTTT TTGCTACTAA 12421 TTATATAGTA TACCATACAT TATCATTCAA AACAACCATC CTGCTCATAA CATCTTTGAA 12481 AAGAAAAATA TATATGTGCA GTATTTTATT AAAGCAACAT TTTATTTAAG AATAAAGTCT 12541 TGTTAATTAC TATATTTTAG ATGCAATGTG ATCTGAAGTT TCTAATTCTG GCCCAACTAA 12601 ATTTCTAGCT CTGTTTCCCT AAACAAATAA TTTGGTTTCT CTGTGCCTGC ATTTTCCCTT 20   12661 TGGAGAAGAA AAGTGCTCTC TCTTGAGTTG ACCGAGAGTC CCATTAGGGA TAGGGAGACT 12721 TAAATGCATC CACAGGGGCA CAGGCAGAGT TGAGCACATA AACGGAGGCC CAAAATCAGC 12781 ATAGAACCAG AAAGATTCAG AGTTGGCCAA GAATGAACAT TGGCTACCAG ACCACAAGTC 12841 AGCATGAGTT GCTCTATGGC ATCAAATTGC AACTTGAGAG TAGATGGGCA GGGTCACTAT 12901 CAAATTAAGC AATCAGGGCA CACAAGTTGC AGTAACACAA CAAGACTAGG CCAGCTCTGG 25   12961 AATCCAGTAA CTCAGTGTCA GCAAGGTTTT GGGTTATAGT TCAAGAAAGT CTAAACAGAG 13021 CCAGTCACAG CACCAAGGAA TGCTCAAGGG AGCTATTGCA GGTTTCTCTG CTAAGAGATT 13081 TATTTCATCC TGGGTGCAGG GTTCGACCTC CAAAGGCCTC AAATCATCAC CGTATCAATG 13141 GATTTCCTGA GGGTAAGCTC CGCTATTTCA CACCTGAACT CCGGAGTCTG TATATTCAGG 13201 GAAGATTGCA TTCTCCTACT GGATTTGGGC TCTCAGAGGG CGTTGTGGGA ACCAGGCCCC 30   13261 TCACAGAATC AAATGGTCCC AACCAGGGAG AAAGAAAATA GTCTTTTTTT TTTTTTTAAT 13321 AGAGATGGGG GTCTCACTAT GCTGCCCAGG CTGGTCTTGA ACTCCTGGGT TCAAGTGATC 13381 CTCCTGCCTC AGCCTCCCAA AGTGCTGGGA TTACAGTGTG AGCCACTGCG CTTGGCCAGA 13441 AATGGTTTTG ATCTGTCTGA ACTGAACCCT ACTGCTTAGG CATAGCCCCA TCCTTGATAA 13501 TCTATTTGCT CCCAAGGACC AAGTCCAAGA TCCTTACAAG AAAGGTCTGC CAGAAAGTAA 35   13561 ATACTGCCCC CACTCCCTGA AGTTTATGAG GTTGATAAGA AAACATAACA GATAAAGTTT 13621 ATTGAGTGCT AACTTTA By “guide RNA” or “gRNA” is meant a polynucleotide which can be specific for a target sequence and can form a complex with a polynucleotide programmable nucleotide 40 binding domain protein (e.g., Cas9 or Cpf1). In an embodiment, the guide polynucleotide is a 2020221355   24 Feb 2026 guide RNA (gRNA). gRNAs can exist as a complex of two or more RNAs, or as a single RNA molecule. gRNAs that exist as a single RNA molecule may be referred to as singleguide RNAs (sgRNAs), though “gRNA” is used interchangeably to refer to guide RNAs that exist as either single molecules or as a complex of two or more molecules. Typically, gRNAs 5 that exist as single RNA species comprise two domains: (1) a domain that shares homology to a target nucleic acid (e.g., and directs binding of a Cas9 complex to the target); and (2) a domain that binds a Cas9 protein. In some embodiments, domain (2) corresponds to a sequence known as a tracrRNA, and comprises a stem-loop structure. For example, in some embodiments, domain (2) is identical or homologous to a tracrRNA as provided in Jinek et 10   al., Science 337:816-821(2012), the entire contents of which is incorporated herein by reference. Other examples of gRNAs (e.g., those including domain 2) can be found in U.S. Provisional Patent Application, U.S.S.N. 61 / 874,682, filed September 6, 2013, entitled "Switchable Cas9 Nucleases and Uses Thereof," and U.S. Provisional Patent Application, U.S.S.N. 61 / 874,746, filed September 6, 2013, entitled "Delivery System For Functional 15 Nucleases," the entire contents of each are hereby incorporated by reference in their entirety. In some embodiments, a gRNA comprises two or more of domains (1) and (2), and may be referred to as an “extended gRNA.” An extended gRNA will bind two or more Cas9 proteins and bind a target nucleic acid at two or more distinct regions, as described herein. The gRNA comprises a nucleotide sequence that complements a target site, which mediates binding of 20 the nuclease / RNA complex to said target site, providing the sequence specificity of the nuclease:RNA complex. As will be appreciated by those skilled in the art, RNA polynucleotide sequences, e.g., gRNA sequences, include the nucleobase uracil (U), a pyrimidine derivative, rather than the nucleobase thymine (T), which is included in DNA polynucleotide sequences. In RNA, uracil base-pairs with adenine and replaces thymine 25 during DNA transcription. By “heterodimer” is meant a fusion protein comprising two domains, such as a wild type TadA domain and a variant of TadA domain (e.g., TadA*8) or two variant TadA domains (e.g., TadA*7.10 and TadA*8 or two TadA*8 domains). “Hybridization” means hydrogen bonding, which may be Watson-Crick, Hoogsteen 30 or reversed Hoogsteen hydrogen bonding, between complementary nucleobases. For example, adenine and thymine are complementary nucleobases that pair through the formation of hydrogen bonds. 2020221355   24 Feb 2026 The term "inhibitor of base repair" or "IBR" refers to a protein that is capable in inhibiting the activity of a nucleic acid repair enzyme, for example a base excision repair (BER) enzyme. In some embodiments, the IBR is an inhibitor of inosine base excision repair. Exemplary inhibitors of base repair include inhibitors of APE1, Endo III, Endo IV, 5 Endo V, Endo VIII, Fpg, hOGGl, hNEILl, T7 Endol, T4PDG, UDG, hSMUGl, and hAAG. In some embodiments, the IBR is an inhibitor of Endo V or hAAG. In some embodiments, the IBR is a catalytically inactive EndoV or a catalytically inactive hAAG. In some embodiments, the base repair inhibitor is an inhibitor of Endo V or hAAG. In some embodiments, the base repair inhibitor is a catalytically inactive EndoV or a catalytically 10 inactive hAAG. In some embodiments, the base repair inhibitor is uracil glycosylase inhibitor (UGI). UGI refers to a protein that is capable of inhibiting a uracil-DNA glycosylase base-excision repair enzyme. In some embodiments, a UGI domain comprises a wild-type UGI or a fragment of a wild-type UGI. In some embodiments, the UGI proteins provided herein 15 include fragments of UGI and proteins homologous to a UGI or a UGI fragment. In some embodiments, the base repair inhibitor is an inhibitor of inosine base excision repair. In some embodiments, the base repair inhibitor is a “catalytically inactive inosine specific nuclease” or “dead inosine specific nuclease. Without wishing to be bound by any particular theory, catalytically inactive inosine glycosylases (e.g., alkyl adenine glycosylase (AAG)) can bind 20 inosine, but cannot create an abasic site or remove the inosine, thereby sterically blocking the newly formed inosine moiety from DNA damage / repair mechanisms. In some embodiments, the catalytically inactive inosine specific nuclease can be capable of binding an inosine in a nucleic acid but does not cleave the nucleic acid. Non-limiting exemplary catalytically inactive inosine specific nucleases include catalytically inactive alkyl adenosine glycosylase 25 (AAG nuclease), for example, from a human, and catalytically inactive endonuclease V (EndoV nuclease), for example, from E. coli. In some embodiments, the catalytically inactive AAG nuclease comprises an E125Q mutation or a corresponding mutation in another AAG nuclease. By “increases” is meant a positive alteration of at least 10%, 25%, 50%, 75%, or 30   100%. An "intein" is a fragment of a protein that is able to excise itself and join the remaining fragments (the exteins) with a peptide bond in a process known as protein splicing. Inteins are also referred to as "protein introns." The process of an intein excising itself and 2020221355   24 Feb 2026 joining the remaining portions of the protein is herein termed "protein splicing" or "intein-mediated protein splicing." In some embodiments, an intein of a precursor protein (an intein containing protein prior to intein-mediated protein splicing) comes from two genes. Such intein is referred to herein as a split intein (e.g., split intein-N and split intein-C). For 5 example, in cyanobacteria, DnaE, the catalytic subunit a of DNA polymerase III, is encoded by two separate genes, dnaE-n and dnaE-c. The intein encoded by the dnaE-n gene may be herein referred as "intein-N." The intein encoded by the dnaE-c gene may be herein referred as "intein-C." Other intein systems may also be used. For example, a synthetic intein based on the 10 dnaE intein, the Cfa-N (e.g., split intein-N) and Cfa-C (e.g., split intein-C) intein pair, has been described (e.g., in Stevens et al., J Am Chem Soc. 2016 Feb. 24; 138(7):2162-5, incorporated herein by reference). Non-limiting examples of intein pairs that may be used in accordance with the present disclosure include: Cfa DnaE intein, Ssp GyrB intein, Ssp DnaX intein, Ter DnaE3 intein, Ter ThyX intein, Rma DnaB intein and Cne Prp8 intein (e.g., as 15 described in U.S. Patent No. 8,394,604, incorporated herein by reference. Exemplary nucleotide and amino acid sequences of inteins are provided. DnaE Intein-N DNA: TGCCTGTCATACGAAACCGAGATACTGACAGTAGAATATGGCCTTCTGCCAATCGGGAAGAT TGTGGAGAAACGGATAGAATGCACAGTTTACTCTGTCGATAACAATGGTAACATTTATACTC 20 AGCCAGTTGCCCAGTGGCACGACCGGGGAGAGCAGGAAGTATTCGAATACTGTCTGGAGGAT GGAAGTCTCATTAGGGCCACTAAGGACCACAAATTTATGACAGTCGATGGCCAGATGCTGCC TATAGACGAAATCTTTGAGCGAGAGTTGGACCTCATGCGAGTTGACAACCTTCCTAAT DnaE Intein-N Protein: CLSYETEILTVEYGLLPIGKIVEKRIECTVYSVDNNGNIYTQPVAQWHDR 25 GEQEVFEYCLEDGSLIRATKDHKFMTVDGQMLPIDEIFERELDLMRVDNLPN DnaE Intein-C DNA: ATGATCAAGATAGCTACAAGGAAGTATCTTGGCAAACAAAACGTTTATGA TATTGGAGTCGAAAGAGATCACAACTTTGCTCTGAAGAACGGATTCATAGCTTCTAAT Intein-C: MIKIATRKYLGKQNVYDIGVERDHNFALKNGFIASN 30 Cfa-N DNA: TGCCTGTCTTATGATACCGAGATACTTACCGTTGAATATGGCTTCTTGCCTATTGGAAAGAT TGTCGAAGAGAGAATTGAATGCACAGTATATACTGTAGACAAGAATGGTTTCGTTTACACAC AGCCCATTGCTCAATGGCACAATCGCGGCGAACAAGAAGTATTTGAGTACTGTCTCGAGGAT 2020221355   24 Feb 2026 GGAAGCATCATACGAGCAACTAAAGATCATAAATTCATGACCACTGACGGGCAGATGTTGCC AATAGATGAGATATTCGAGCGGGGCTTGGATCTCAAACAAGTGGATGGATTGCCA Cfa-N Protein: CLSYDTEILTVEYGFLPIGKIVEERIECTVYTVDKNGFVYTQPIAQWHNRGEQEVFEYCLED 5 GSIIRATKDHKFMTTDGQMLPIDEIFERGLDLKQVDGLP Cfa-C DNA: ATGAAGAGGACTGCCGATGGATCAGAGTTTGAATCTCCCAAGAAGAAGAGGAAAGTAAAGAT AATATCTCGAAAAAGTCTTGGTACCCAAAATGTCTATGATATTGGAGTGGAGAAAGATCACA ACTTCCTTCTCAAGAACGGTCTCGTAGCCAGCAAC 10 Cfa-C Protein: MKRTADGSEFESPKKKRKVKIISRKSLGTQNVYDIGVEKDHNFLLKNGLVASN Intein-N and intein-C may be fused to the N-terminal portion of the split Cas9 and the C-terminal portion of the split Cas9, respectively, for the joining of the N-terminal portion of the split Cas9 and the C-terminal portion of the split Cas9. For example, in some 15 embodiments, an intein-N is fused to the C-terminus of the N-terminal portion of the split Cas9, i.e., to form a structure of N--[N-terminal portion of the split Cas9]-[intein-N]--C. In some embodiments, an intein-C is fused to the N-terminus of the C-terminal portion of the split Cas9, i.e., to form a structure of N-[intein-C]--[C-terminal portion of the split Cas9]-C. The mechanism of intein-mediated protein splicing for joining the proteins the inteins are 20    fused to (e.g., split Cas9) is known in the art, e.g., as described in Shah et al., Chem Sci. 2014; 5(1):446-461, incorporated herein by reference. Methods for designing and using inteins are known in the art and described, for example by WO2014004336, WO2017132580, US20150344549, and US20180127780, each of which is incorporated herein by reference in their entirety. 25           The terms "isolated," "purified," or "biologically pure" refer to material that is free to varying degrees from components which normally accompany it as found in its native state. "Isolate" denotes a degree of separation from original source or surroundings. "Purify" denotes a degree of separation that is higher than isolation. A "purified" or "biologically pure" protein is sufficiently free of other materials such that any impurities do not materially 30 affect the biological properties of the protein or cause other adverse consequences. That is, a nucleic acid or peptide of this disclosure is purified if it is substantially free of cellular material, viral material, or culture medium when produced by recombinant DNA techniques, or chemical precursors or other chemicals when chemically synthesized. Purity and 2020221355   24 Feb 2026 homogeneity are typically determined using analytical chemistry techniques, for example, polyacrylamide gel electrophoresis or high-performance liquid chromatography. The term "purified" can denote that a nucleic acid or protein gives rise to essentially one band in an electrophoretic gel. For a protein that can be subjected to modifications, for example, 5 phosphorylation or glycosylation, different modifications may give rise to different isolated proteins, which can be separately purified. By "isolated polynucleotide" is meant a nucleic acid (e.g., a DNA) that is free of the genes which, in the naturally-occurring genome of the organism from which the nucleic acid molecule of the disclosure is derived, flank the gene. The term therefore includes, for 10 example, a recombinant DNA that is incorporated into a vector; into an autonomously replicating plasmid or virus; or into the genomic DNA of a prokaryote or eukaryote; or that exists as a separate molecule (for example, a cDNA or a genomic or cDNA fragment produced by PCR or restriction endonuclease digestion) independent of other sequences. In addition, the term includes an RNA molecule that is transcribed from a DNA molecule, as 15 well as a recombinant DNA that is part of a hybrid gene encoding additional polypeptide sequence. By an "isolated polypeptide" is meant a polypeptide of the disclosure that has been separated from components that naturally accompany it. Typically, the polypeptide is isolated when it is at least 60%, by weight, free from the proteins and naturally-occurring 20 organic molecules with which it is naturally associated. Preferably, the preparation is at least 75%, more preferably at least 90%, and most preferably at least 99%, by weight, a polypeptide of the disclosure. An isolated polypeptide of the disclosure may be obtained, for example, by extraction from a natural source, by expression of a recombinant nucleic acid encoding such a polypeptide; or by chemically synthesizing the protein. Purity can be 25 measured by any appropriate method, for example, column chromatography, polyacrylamide gel electrophoresis, or by HPLC analysis. The term “linker,” as used herein, can refer to a covalent linker (e.g., covalent bond), a non-covalent linker, a chemical group, or a molecule linking two molecules or moieties, e.g., two components of a protein complex or a ribonucleocomplex, or two domains of a 30 fusion protein, such as, for example, a polynucleotide programmable DNA binding domain (e.g., dCas9) and a deaminase domain (e.g., an adenosine deaminase). A linker can join different components of, or different portions of components of, a base editor system. For example, in some embodiments, a linker can join a guide polynucleotide binding domain of a 2020221355   24 Feb 2026 polynucleotide programmable nucleotide binding domain and a catalytic domain of a deaminase. In some embodiments, a linker can join a CRISPR polypeptide and a deaminase. In some embodiments, a linker can join a Cas9 and a deaminase. In some embodiments, a linker can join a dCas9 and a deaminase. In some embodiments, a linker can join a nCas9 5 and a deaminase. In some embodiments, a linker can join a guide polynucleotide and a deaminase. In some embodiments, a linker can join a deaminating component and a polynucleotide programmable nucleotide binding component of a base editor system. In some embodiments, a linker can join a RNA-binding portion of a deaminating component and a polynucleotide programmable nucleotide binding component of a base editor system. 10 In some embodiments, a linker can join a RNA-binding portion of a deaminating component and a RNA-binding portion of a polynucleotide programmable nucleotide binding component of a base editor system. A linker can be positioned between, or flanked by, two groups, molecules, or other moieties and connected to each one via a covalent bond or non-covalent interaction, thus connecting the two. In some embodiments, the linker can be an organic 15 molecule, group, polymer, or chemical moiety. In some embodiments, the linker can be a polynucleotide. In some embodiments, the linker can be a DNA linker. In some embodiments, the linker can be a RNA linker. In some embodiments, a linker can comprise an aptamer capable of binding to a ligand. In some embodiments, the ligand may be carbohydrate, a peptide, a protein, or a nucleic acid. In some embodiments, the linker may 20 comprise an aptamer may be derived from a riboswitch. The riboswitch from which the aptamer is derived may be selected from a theophylline riboswitch, a thiamine pyrophosphate (TPP) riboswitch, an adenosine cobalamin (AdoCbl) riboswitch, an S-adenosyl methionine (SAM) riboswitch, an SAH riboswitch, a flavin mononucleotide (FMN) riboswitch, a tetrahydrofolate riboswitch, a lysine riboswitch, a glycine riboswitch, a purine riboswitch, a 25 GlmS riboswitch, or a pre-queosine1 (PreQ1) riboswitch. In some embodiments, a linker may comprise an aptamer bound to a polypeptide or a protein domain, such as a polypeptide ligand. In some embodiments, the polypeptide ligand may be a K Homology (KH) domain, a MS2 coat protein domain, a PP7 coat protein domain, a SfMu Com coat protein domain, a sterile alpha motif, a telomerase Ku binding motif and Ku protein, a telomerase Sm7 binding 30 motif and Sm7 protein, or a RNA recognition motif. In some embodiments, the polypeptide ligand may be a portion of a base editor system component. For example, a nucleobase editing component may comprise a deaminase domain and a RNA recognition motif. 2020221355   24 Feb 2026 In some embodiments, the linker can be an amino acid or a plurality of amino acids (e.g., a peptide or protein). In some embodiments, the linker can be about 5-100 amino acids in length, for example, about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 20-30, 3040, 40-50, 50-60, 60-70, 70-80, 80-90, or 90-100 amino acids in length. In some 5 embodiments, the linker can be about 100-150, 150-200, 200-250, 250-300, 300-350, 350400, 400-450, or 450-500 amino acids in length. Longer or shorter linkers can be also contemplated. In some embodiments, a linker joins a gRNA binding domain of an RNA-programmable nuclease, including a Cas9 nuclease domain, and the catalytic domain of a 10   nucleic-acid editing protein (e.g., adenosine deaminase). In some embodiments, a linker joins a dCas9 and a nucleic-acid editing protein. For example, the linker is positioned between, or flanked by, two groups, molecules, or other moieties and connected to each one via a covalent bond, thus connecting the two. In some embodiments, the linker is an amino acid or a plurality of amino acids (e.g., a peptide or protein). In some embodiments, the 15 linker is an organic molecule, group, polymer, or chemical moiety. In some embodiments, the linker is 5-200 amino acids in length, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 35, 45, 50, 55, 60, 60, 65, 70, 70, 75, 80, 85, 90, 90, 95, 100, 101, 102, 103, 104, 105, 110, 120, 130, 140, 150, 160, 175, 180, 190, or 200 amino acids in length. Longer or shorter linkers are also contemplated. 20          In some embodiments, the domains of the nucleobase editor are fused via a linker that comprises the amino acid sequence of SGGSSGSETPGTSESATPESSGGS, SGGSSGGSSGSETPGTSESATPESSGGSSGGS, or GGSGGSPGSPAGSPTSTEEGTSESATPESGPGTSTEPSEGSAPGSPAGSPTSTEEGTSTE PSEGSAPGTSTEPSEGSAPGTSESATPESGPGSEPATSGGSGGS. In some embodiments, 25 domains of the nucleobase editor are fused via a linker comprising the amino acid sequence SGSETPGTSESATPES, which may also be referred to as the XTEN linker. In some embodiments, a linker comprises the amino acid sequence SGGS. In some embodiments, a linker comprises (SGGS)n, (GGGS)n, (GGGGS) n, (G)n, (EAAAK)n, (GGS)n, SGSETPGTSESATPES, or (XP)n motif, or a combination of any of these, wherein n is 30 independently an integer between 1 and 30, and wherein X is any amino acid. In some embodiments, n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. In some embodiments, the linker is 24 amino acids in length. In some embodiments, the linker comprises the amino acid sequence SGGSSGGSSGSETPGTSESATPES. In some 2020221355   24 Feb 2026 embodiments, the linker is 40 amino acids in length. In some embodiments, the linker comprises the amino acid sequence SGGSSGGSSGSETPGTSESATPESSGGSSGGSSGGSSGGS. In some embodiments, the linker is 64 amino acids in length. In some embodiments, the linker comprises the amino acid 5 sequence SGGSSGGSSGSETPGTSESATPESSGGSSGGSSGGSSGGSSGSETPGTSESATPESSGGS SGGS. In some embodiments, the linker is 92 amino acids in length. In some embodiments, the linker comprises the amino acid sequence PGSPAGSPTSTEEGTSESATPESGPGTSTEPSEGSAPGSPAGSPTSTEEGTSTEPSEGSAPG 10 TSTEPSEGSAPGTSESATPESGPGSEPATS. By “marker” is meant any protein or polynucleotide having an alteration in expression level or activity that is associated with a disease or disorder. The term “mutation,” as used herein, refers to a substitution of a residue within a sequence, e.g., a nucleic acid or amino acid sequence, with another residue, or a deletion or 15 insertion of one or more residues within a sequence. Mutations are typically described herein by identifying the original residue followed by the position of the residue within the sequence and by the identity of the newly substituted residue. Various methods for making the amino acid substitutions (mutations) provided herein are well known in the art, and are provided by, for example, Green and Sambrook, Molecular Cloning: A Laboratory Manual (4th ed., Cold 20 Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (2012)). In some embodiments, the presently disclosed base editors can efficiently generate an “intended mutation,” such as a point mutation, in a nucleic acid (e.g., a nucleic acid within a genome of a subject) without generating a significant number of unintended mutations, such as unintended point mutations. In some embodiments, an intended mutation is a mutation that is generated by a specific base 25   editor (e.g., adenosine base editor) bound to a guide polynucleotide (e.g., gRNA), specifically designed to generate the intended mutation. In general, mutations made or identified in a sequence (e.g., an amino acid sequence as described herein) are numbered in relation to a reference (or wild-type) sequence, i.e., a sequence that does not contain the mutations. The skilled practitioner in the art would readily 30 understand how to determine the position of mutations in amino acid and nucleic acid sequences relative to a reference sequence. The term “non-conservative mutations” involve amino acid substitutions between different groups, for example, lysine for tryptophan, or phenylalanine for serine, etc. In this 2020221355   24 Feb 2026 case, it is preferable for the non-conservative amino acid substitution to not interfere with, or inhibit the biological activity of, the functional variant. The non-conservative amino acid substitution can enhance the biological activity of the functional variant, such that the biological activity of the functional variant is increased as compared to the wild-type protein. 5          The term “nuclear localization sequence,” “nuclear localization signal,” or “NLS” refers to an amino acid sequence that promotes import of a protein into the cell nucleus. Nuclear localization sequences are known in the art and described, for example, in Plank et al., International PCT application, PCT / EP2000 / 011690, filed November 23, 2000, published as WO / 2001 / 038547 on May 31, 2001, the contents of which are incorporated herein by 10 reference for their disclosure of exemplary nuclear localization sequences. In other embodiments, the NLS is an optimized NLS described, for example, by Koblan et al., Nature Biotech. 2018 doi:10.1038 / nbt.4172. In some embodiments, an NLS comprises an amino acid sequence selected from: KRTADGSEFESPKKKRKV, KRPAATKKAGQAKKKK, KKTELQTTNAENKTKKL, KRGINDRNFWRGENGRKTR, RKSGKIAAIVVKRPRK, PKKKRKV, 15 or MDSLLMNRRKFLYQFKNVRWAKGRRETYLC. The terms “nucleic acid” and “nucleic acid molecule,” as used herein, refer to a compound comprising a nucleobase and an acidic moiety, e.g., a nucleoside, a nucleotide, or a polymer of nucleotides. Typically, polymeric nucleic acids, e.g., nucleic acid molecules comprising three or more nucleotides are linear molecules, in which adjacent nucleotides are 20 linked to each other via a phosphodiester linkage. In some embodiments, “nucleic acid” refers to individual nucleic acid residues (e.g. nucleotides and / or nucleosides). In some embodiments, “nucleic acid” refers to an oligonucleotide chain comprising three or more individual nucleotide residues. As used herein, the terms “oligonucleotide” and “polynucleotide” can be used interchangeably to refer to a polymer of nucleotides (e.g., a 25 string of at least three nucleotides). In some embodiments, “nucleic acid” encompasses RNA as well as single and / or double-stranded DNA. Nucleic acids may be naturally occurring, for example, in the context of a genome, a transcript, an mRNA, tRNA, rRNA, siRNA, snRNA, a plasmid, cosmid, chromosome, chromatid, or other naturally occurring nucleic acid molecule. On the other hand, a nucleic acid molecule may be a non-naturally occurring 30 molecule, e.g., a recombinant DNA or RNA, an artificial chromosome, an engineered genome, or fragment thereof, or a synthetic DNA, RNA, DNA / RNA hybrid, or including non-naturally occurring nucleotides or nucleosides. Furthermore, the terms “nucleic acid,” “DNA,” “RNA,” and / or similar terms include nucleic acid analogs, e.g., analogs having other 2020221355   24 Feb 2026 than a phosphodiester backbone. Nucleic acids can be purified from natural sources, produced using recombinant expression systems and optionally purified, chemically synthesized, etc. Where appropriate, e.g., in the case of chemically synthesized molecules, nucleic acids can comprise nucleoside analogs such as analogs having chemically modified 5 bases or sugars, and backbone modifications. A nucleic acid sequence is presented in the 5’ to 3' direction unless otherwise indicated. In some embodiments, a nucleic acid is or comprises natural nucleosides (e.g. adenosine, thymidine, guanosine, cytidine, uridine, deoxyadenosine, deoxythymidine, deoxyguanosine, and deoxycytidine); nucleoside analogs (e.g., 2-aminoadenosine, 2-thiothymidine, inosine, pyrrolo-pyrimidine, 3-methyl adenosine, 10 5-methylcytidine, 2-aminoadenosine, C5-bromouridine, C5-fluorouridine, C5-iodouridine, C5-propynyl-uridine, C5-propynyl-cytidine, C5-methylcytidine, 2-aminoadenosine, 7-deazaadenosine, 7-deazaguanosine, 8-oxoadenosine, 8-oxoguanosine, O(6)-methylguanine, and 2-thiocytidine); chemically modified bases; biologically modified bases (e.g., methylated bases); intercalated bases; modified sugars ( 2'-e.g., fluororibose, ribose, 2'-deoxyribose, 15 arabinose, and hexose); and / or modified phosphate groups (e.g., phosphorothioates and 5'-N-phosphoramidite linkages). The term "nucleic acid programmable DNA binding protein" or "napDNAbp" may be used interchangeably with “polynucleotide programmable nucleotide binding domain” to refer to a protein that associates with a nucleic acid (e.g., DNA or RNA), such as a guide 20 nucleic acid or guide polynucleotide (e.g., gRNA), that guides the napDNAbp to a specific nucleic acid sequence. In some embodiments, the polynucleotide programmable nucleotide binding domain is a polynucleotide programmable DNA binding domain. In some embodiments, the polynucleotide programmable nucleotide binding domain is a polynucleotide programmable RNA binding domain. In some embodiments, the 25 polynucleotide programmable nucleotide binding domain is a Cas9 protein. A Cas9 protein can associate with a guide RNA that guides the Cas9 protein to a specific DNA sequence that is complementary to the guide RNA. In some embodiments, the napDNAbp is a Cas9 domain, for example a nuclease active Cas9, a Cas9 nickase (nCas9), or a nuclease inactive Cas9 (dCas9). Non-limiting examples of nucleic acid programmable DNA binding proteins 30   include, Cas9 (e.g., dCas9 and nCas9), Cas12a / Cpfl, Cas12b / C2cl, Cas12c / C2c3, Cas12d / CasY, Cas12e / CasX, Cas12g, Cas12h, and Cas12i. Non-limiting examples of Cas enzymes include Cas1, Cas1B, Cas2, Cas3, Cas4, Cas5, Cas5d, Cas5t, Cas5h, Cas5a, Cas6, Cas7, Cas8, Cas8a, Cas8b, Cas8c, Cas9 (also known as Csn1 or Csx12), Cas10, Cas10d, 2020221355   24 Feb 2026 Cas12a / Cpfl, Cas12b / C2cl, Cas12c / C2c3, Cas12d / CasY, Cas12e / CasX, Cas12g, Cas12h, Cas12i, Csy1 , Csy2, Csy3, Csy4, Cse1, Cse2, Cse3, Cse4, Cse5e, Csc1, Csc2, Csa5, Csn1, Csn2, Csm1, Csm2, Csm3, Csm4, Csm5, Csm6, Cmr1, Cmr3, Cmr4, Cmr5, Cmr6, Csb1, Csb2, Csb3, Csx17, Csx14, Csx10, Csx16, CsaX, Csx3, Csx1, Csx1S, Csx11, Csf1, Csf2, 5 CsO, Csf4, Csd1, Csd2, Cst1, Cst2, Csh1, Csh2, Csa1, Csa2, Csa3, Csa4, Csa5, Type II Cas effector proteins, Type V Cas effector proteins, Type VI Cas effector proteins, CARF, DinG, homologues thereof, or modified or engineered versions thereof. Other nucleic acid programmable DNA binding proteins are also within the scope of this disclosure, although they may not be specifically listed in this disclosure. See, e.g., Makarova et al. 10 “Classification and Nomenclature of CRISPR-Cas Systems: Where from Here?” CRISPR J. 2018 Oct;1:325-336. doi: 10.1089 / crispr.2018.0033; Yan et al., “Functionally diverse type V CRISPR-Cas systems” Science. 2019 Jan 4;363(6422):88-91. doi: 10.1126 / science.aav7271, the entire contents of each are hereby incorporated by reference. The term “nucleobase,” “nitrogenous base,” or “base,” used interchangeably herein, 15 refers to a nitrogen-containing biological compound that forms a nucleoside, which in turn is a component of a nucleotide. The ability of nucleobases to form base pairs and to stack one upon another leads directly to long-chain helical structures such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Five nucleobases - adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U) - are called primary or canonical. Adenine and guanine are 20 derived from purine, and cytosine, uracil, and thymine are derived from pyrimidine. DNA and RNA can also contain other (non-primary) bases that are modified. Non-limiting exemplary modified nucleobases can include hypoxanthine, xanthine, 7-methylguanine, 5,6-dihydrouracil, 5-methylcytosine (m5C), and 5-hydromethylcytosine. Hypoxanthine and xanthine can be created through mutagen presence, both of them through deamination 25 (replacement of the amine group with a carbonyl group). Hypoxanthine can be modified from adenine. Xanthine can be modified from guanine. Uracil can result from deamination of cytosine. A “nucleoside” consists of a nucleobase and a five carbon sugar (either ribose or deoxyribose). Examples of a nucleoside include adenosine, guanosine, uridine, cytidine, 5-methyluridine (m5U), deoxyadenosine, deoxyguanosine, thymidine, deoxyuridine, and 30 deoxycytidine. Examples of a nucleoside with a modified nucleobase includes inosine (I), xanthosine (X), 7-methylguanosine (m7G), dihydrouridine (D), 5-methylcytidine (m5C), and pseudouridine (T). A “nucleotide” consists of a nucleobase, a five carbon sugar (either ribose or deoxyribose), and at least one phosphate group. 2020221355   24 Feb 2026 The terms “nucleobase editing domain” or “nucleobase editing protein,” as used herein, refers to a protein or enzyme that can catalyze a nucleobase modification in RNA or DNA, such as cytosine (or cytidine) to uracil (or uridine) or thymine (or thymidine), and adenine (or adenosine) to hypoxanthine (or inosine) deaminations, as well as non-templated 5 nucleotide additions and insertions. In some embodiments, the nucleobase editing domain is a deaminase domain (e.g., an adenine deaminase or an adenosine deaminase). In some embodiments, the nucleobase editing domain can be a naturally occurring nucleobase editing domain. In some embodiments, the nucleobase editing domain can be an engineered or evolved nucleobase editing domain from the naturally occurring nucleobase editing domain. 10 The nucleobase editing domain can be from any organism, such as a bacterium, human, chimpanzee, gorilla, monkey, cow, dog, rat, or mouse. As used herein, “obtaining” as in “obtaining an agent” includes synthesizing, purchasing, or otherwise acquiring the agent. A “patient” or “subject” as used herein refers to a mammalian subject or individual 15 diagnosed with, at risk of having or developing, or suspected of having or developing a disease or a disorder. In some embodiments, the term “patient” refers to a mammalian subject with a higher than average likelihood of developing a disease or a disorder. Exemplary patients can be humans, non-human primates, cats, dogs, pigs, cattle, cats, horses, camels, llamas, goats, sheep, rodents (e.g., mice, rabbits, rats, or guinea pigs) and other 20 mammalians that can benefit from the therapies disclosed herein. Exemplary human patients can be male and / or female. “Patient in need thereof” or “subject in need thereof” is referred to herein as a patient diagnosed with or suspected of having a disease or disorder, for instance, but not restricted to Glycogen Storage Disease Type 1 (GSD1 or Von Gierke Disease). 25          The terms “pathogenic mutation,” “pathogenic variant,” “disease casing mutation,” “disease causing variant,” “deleterious mutation,” or “predisposing mutation” refers to a genetic alteration or mutation that increases an individual’s susceptibility or predisposition to a certain disease or disorder. In some embodiments, the pathogenic mutation comprises at least one wild-type amino acid substituted by at least one pathogenic amino acid in a protein 30 encoded by a gene. The terms “protein,” “peptide,” “polypeptide,” and their grammatical equivalents are used interchangeably herein, and refer to a polymer of amino acid residues linked together by peptide (amide) bonds. The terms refer to a protein, peptide, or polypeptide of any size, 2020221355   24 Feb 2026 structure, or function. Typically, a protein, peptide, or polypeptide will be at least three amino acids long. A protein, peptide, or polypeptide can refer to an individual protein or a collection of proteins. One or more of the amino acids in a protein, peptide, or polypeptide can be modified, for example, by the addition of a chemical entity such as a carbohydrate 5 group, a hydroxyl group, a phosphate group, a farnesyl group, an isofarnesyl group, a fatty acid group, a linker for conjugation, functionalization, or other modifications, etc. A protein, peptide, or polypeptide can also be a single molecule or can be a multi-molecular complex. A protein, peptide, or polypeptide can be just a fragment of a naturally occurring protein or peptide. A protein, peptide, or polypeptide can be naturally occurring, recombinant, or 10 synthetic, or any combination thereof. The term “fusion protein” as used herein refers to a hybrid polypeptide which comprises protein domains from at least two different proteins. One protein can be located at the amino-terminal (N-terminal) portion of the fusion protein or at the carboxy-terminal (C-terminal) protein thus forming an amino-terminal fusion protein or a carboxy-terminal fusion protein, respectively. A protein can comprise different domains, 15 for example, a nucleic acid binding domain (e.g., the gRNA binding domain of Cas9 that directs the binding of the protein to a target site) and a nucleic acid cleavage domain, or a catalytic domain of a nucleic acid editing protein. In some embodiments, a protein comprises a proteinaceous part, e.g., an amino acid sequence constituting a nucleic acid binding domain, and an organic compound, e.g., a compound that can act as a nucleic acid cleavage agent. In 20 some embodiments, a protein is in a complex with, or is in association with, a nucleic acid, e.g., RNA or DNA. Any of the proteins provided herein can be produced by any method known in the art. For example, the proteins provided herein can be produced via recombinant protein expression and purification, which is especially suited for fusion proteins comprising a peptide linker. Methods for recombinant protein expression and purification are well 25 known, and include those described by Green and Sambrook, Molecular Cloning: A Laboratory Manual (4th ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (2012)), the entire contents of which are incorporated herein by reference. Polypeptides and proteins disclosed herein (including functional portions and functional variants thereof) can comprise synthetic amino acids in place of one or more 30 naturally-occurring amino acids. Such synthetic amino acids are known in the art, and include, for example, aminocyclohexane carboxylic acid, norleucine, a-amino n-decanoic acid, homoserine, S-acetylaminomethyl-cysteine, trans-3- and trans-4-hydroxyproline, 4-aminophenylalanine, 4-nitrophenylalanine, 4-chlorophenylalanine, 4-carboxyphenylalanine, 2020221355   24 Feb 2026 P-phenylserine P-hydroxyphenylalanine, phenylglycine, a-naphthylalanine, cyclohexylalanine, cyclohexylglycine, indoline-2-carboxylic acid, 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, aminomalonic acid, aminomalonic acid monoamide, N’-benzyl-N’-methyl-lysine, N’,N’-dibenzyl-lysine, 6-hydroxylysine, ornithine, 5 a-aminocyclopentane carboxylic acid, a-aminocyclohexane carboxylic acid, a-aminocycloheptane carboxylic acid, a-(2-amino-2-norbornane)-carboxylic acid, a,Y— diaminobutyric acid, a,P-diaminopropionic acid, homophenylalanine, and a-tert-butylglycine. The polypeptides and proteins can be associated with post-translational modifications of one or more amino acids of the polypeptide constructs. Non-limiting examples of post-10 translational modifications include phosphorylation, acylation including acetylation and formylation, glycosylation (including N-linked and O-linked), amidation, hydroxylation, alkylation including methylation and ethylation, ubiquitylation, addition of pyrrolidone carboxylic acid, formation of disulfide bridges, sulfation, myristoylation, palmitoylation, isoprenylation, farnesylation, geranylation, glypiation, lipoylation and iodination. 15          The term "recombinant" as used herein in the context of proteins or nucleic acids refers to proteins or nucleic acids that do not occur in nature, but are the product of human engineering. For example, in some embodiments, a recombinant protein or nucleic acid molecule comprises an amino acid or nucleotide sequence that comprises at least one, at least two, at least three, at least four, at least five, at least six, or at least seven mutations as 20 compared to any naturally occurring sequence. By “reduces” is meant a negative alteration of at least 10%, 25%, 50%, 75%, or 100%. By “reference” is meant a standard or control condition. In one embodiment, the reference is a wild-type or healthy cell. In other embodiments and without limitation, a 25 reference is an untreated cell that is not subjected to a test condition, or is subjected to placebo or normal saline, medium, buffer, and / or a control vector that does not harbor a polynucleotide of interest. A “reference sequence” is a defined sequence used as a basis for sequence comparison. A reference sequence may be a subset of or the entirety of a specified sequence; 30 for example, a segment of a full-length cDNA or gene sequence, or the complete cDNA or gene sequence. For polypeptides, the length of the reference polypeptide sequence will generally be at least about 16 amino acids, at least about 20 amino acids, at least about 25 amino acids, about 35 amino acids, about 50 amino acids, or about 100 amino acids. For 2020221355   24 Feb 2026 nucleic acids, the length of the reference nucleic acid sequence will generally be at least about 50 nucleotides, at least about 60 nucleotides, at least about 75 nucleotides, about 100 nucleotides or about 300 nucleotides or any integer thereabout or therebetween. In some embodiments, a reference sequence is a wild-type sequence of a protein of interest. In other 5 embodiments, a reference sequence is a polynucleotide sequence encoding a wild-type protein. The term "RNA-programmable nuclease," and "RNA-guided nuclease" are used with (e.g., binds or associates with) one or more RNA(s) that is not a target for cleavage. In some embodiments, an RNA-programmable nuclease, when in a complex with an RNA, may be 10 referred to as a nuclease:RNA complex. Typically, the bound RNA(s) is referred to as a guide RNA (gRNA). gRNAs can exist as a complex of two or more RNAs, or as a single RNA molecule. gRNAs that exist as a single RNA molecule may be referred to as singleguide RNAs (sgRNAs), though "gRNA" is used interchangeably to refer to guide RNAs that exist as either single molecules or as a complex of two or more molecules. Typically, gRNAs 15 that exist as single RNA species comprise two domains: (1) a domain that shares homology to a target nucleic acid (e.g., and directs binding of a Cas9 complex to the target); and (2) a domain that binds a Cas9 protein. In some embodiments, domain (2) corresponds to a sequence known as a tracrRNA, and comprises a stem-loop structure. For example, in some embodiments, domain (2) is identical or homologous to a tracrRNA as provided in Jinek et 20 ah, Science 337:816-821(2012), the entire contents of which is incorporated herein by reference. Other examples of gRNAs (e.g., those including domain 2) can be found in U.S. Provisional Patent Application, U.S.S.N. 61 / 874,682, filed September 6, 2013, entitled "Switchable Cas9 Nucleases and Uses Thereof," and U.S. Provisional Patent Application, U.S.S.N. 61 / 874,746, filed September 6, 2013, entitled "Delivery System For Functional 25 Nucleases," the entire contents of each are hereby incorporated by reference in their entirety. In some embodiments, a gRNA comprises two or more of domains (1) and (2), and may be referred to as an "extended gRNA." For example, an extended gRNA will, e.g., bind two or more Cas9 proteins and bind a target nucleic acid at two or more distinct regions, as described herein. The gRNA comprises a nucleotide sequence that complements a target site, 30 which mediates binding of the nuclease / RNA complex to said target site, providing the sequence specificity of the nuclease:RNA complex. In some embodiments, the RNA-programmable nuclease is the (CRISPR-associated system) Cas9 endonuclease, for example, Cas9 (Casnl) from Streptococcus pyogenes (see, e.g., 2020221355   24 Feb 2026 "Complete genome sequence of an Ml strain of Streptococcus pyogenes." Ferretti J.J., McShan W.M., Ajdic D.J., Savic D.J., Savic G., Lyon K., Primeaux C, Sezate S., Suvorov A.N., Kenton S., Lai H.S., Lin S.P., Qian Y., Jia H.G., Najar F.Z., Ren Q., Zhu H., Song L., White J., Yuan X., Clifton S.W., Roe B.A., McLaughlin R.E., Proc. Natl. Acad. Sci. U.S.A. 98:46585   4663(2001); "CRISPR RNA maturation by trans-encoded small RNA and host factor RNase III." Deltcheva E., Chylinski K., Sharma CM., Gonzales K., Chao Y., Pirzada Z.A., Eckert M.R., Vogel J., Charpentier E., Nature 471:602-607(2011). Because RNA-programmable nucleases (e.g., Cas9) use RNA:DNA hybridization to target DNA cleavage sites, these proteins are able to be targeted, in principle, to any sequence 10 specified by the guide RNA. Methods of using RNA-programmable nucleases, such as Cas9, for site-specific cleavage (e.g., to modify a genome) are known in the art (see e.g., Cong, L. et al., Multiplex genome engineering using CRISPR / Cas systems. Science 339, 819-823 (2013); Mali, P. et ah, RNA-guided human genome engineering via Cas9. Science 339, 823-826 (2013); Hwang, W.Y. et al., Efficient genome editing in zebrafish using a CRISPR-Cas system. 15 Nature biotechnology 31, 227-229 (2013); Jinek, M. et ah, RNA-programmed genome editing in human cells. eLife 2, e00471 (2013); Dicarlo, J.E. et al., Genome engineering in Saccharomyces cerevisiae using CRISPR-Cas systems. Nucleic acids research (2013); Jiang, W. et ah RNA-guided editing of bacterial genomes using CRISPR-Cas systems. Nature biotechnology 31, 233-239 (2013); the entire contents of each of which are incorporated herein 20 by reference). The term “single nucleotide polymorphism (SNP)” is a variation in a single nucleotide that occurs at a specific position in the genome, where each variation is present to some appreciable degree within a population (e.g., > 1%). For example, at a specific base position in the human genome, the C nucleotide can appear in most individuals, but in a minority of 25 individuals, the position is occupied by an A. This means that there is a SNP at this specific position, and the two possible nucleotide variations, C or A, are said to be alleles for this position. SNPs underlie differences in susceptibility to disease. The severity of illness and the way our body responds to treatments are also manifestations of genetic variations. SNPs can fall within coding regions of genes, non-coding regions of genes, or in the intergenic 30 regions (regions between genes). In some embodiments, SNPs within a coding sequence do not necessarily change the amino acid sequence of the protein that is produced, due to degeneracy of the genetic code. SNPs in the coding region are of two types: synonymous and nonsynonymous SNPs. Synonymous SNPs do not affect the protein sequence, while 2020221355   24 Feb 2026 nonsynonymous SNPs change the amino acid sequence of protein. The nonsynonymous SNPs are of two types: missense and nonsense. SNPs that are not in protein-coding regions can still affect gene splicing, transcription factor binding, messenger RNA degradation, or the sequence of noncoding RNA. Gene expression affected by this type of SNP is referred to as 5 an eSNP (expression SNP) and can be upstream or downstream from the gene. A single nucleotide variant (SNV) is a variation in a single nucleotide without any limitations of frequency and can arise in somatic cells. A somatic single nucleotide variation can also be called a single-nucleotide alteration. By "specifically binds" is meant a nucleic acid molecule, polypeptide, or complex 10   thereof (e.g., a nucleic acid programmable DNA binding domain and guide nucleic acid), compound, or molecule that recognizes and binds a polypeptide and / or nucleic acid molecule of the disclosure, but which does not substantially recognize and bind other molecules in a sample, for example, a biological sample. Nucleic acid molecules useful in the methods of the present disclosure include any 15 nucleic acid molecule that encodes a polypeptide of this disclosure or a fragment thereof. Such nucleic acid molecules need not be 100% identical with an endogenous nucleic acid sequence, but will typically exhibit substantial identity. Polynucleotides having “substantial identity” to an endogenous sequence are typically capable of hybridizing with at least one strand of a double-stranded nucleic acid molecule. Nucleic acid molecules useful in the 20 methods of the present disclosure include any nucleic acid molecule that encodes a polypeptide of this disclosure or a fragment thereof. Such nucleic acid molecules need not be 100% identical with an endogenous nucleic acid sequence, but will typically exhibit substantial identity. Polynucleotides having “substantial identity” to an endogenous sequence are typically capable of hybridizing with at least one strand of a double-stranded nucleic acid 25 molecule. By "hybridize" is meant pair to form a double-stranded molecule between complementary polynucleotide sequences (e.g., a gene described herein), or portions thereof, under various conditions of stringency. (See, e.g., Wahl, G. M. and S. L. Berger (1987) Methods Enzymol. 152:399; Kimmel, A. R. (1987) Methods Enzymol. 152:507). For example, stringent salt concentration will ordinarily be less than about 750 mM 30 NaCl and 75 mM trisodium citrate, preferably less than about 500 mM NaCl and 50 mM trisodium citrate, and more preferably less than about 250 mM NaCl and 25 mM trisodium citrate. Low stringency hybridization can be obtained in the absence of organic solvent, e.g., formamide, while high stringency hybridization can be obtained in the presence of at least 2020221355   24 Feb 2026 about 35% formamide, and more preferably at least about 50% formamide. Stringent temperature conditions will ordinarily include temperatures of at least about 30° C, more preferably of at least about 37° C, and most preferably of at least about 42° C. Varying additional parameters, such as hybridization time, the concentration of detergent, e.g., sodium 5 dodecyl sulfate (SDS), and the inclusion or exclusion of carrier DNA, are well known to those skilled in the art. Various levels of stringency are accomplished by combining these various conditions as needed. In a one: embodiment, hybridization will occur at 30° C in 750 mM NaCl, 75 mM trisodium citrate, and 1% SDS. In another embodiment, hybridization will occur at 37° C in 500 mM NaCl, 50 mM trisodium citrate, 1% SDS, 35% formamide, and 10   100 ug ml denatured salmon sperm DNA (ssDNA). In another embodiment, hybridization will occur at 42° C in 250 mM NaCl, 25 mM trisodium citrate, 1% SDS, 50% formamide, and 200 gg / ml ssDNA. Useful variations on these conditions will be readily apparent to those skilled in the art. For most applications, washing steps that follow hybridization will also vary in 15 stringency. Wash stringency conditions can be defined by salt concentration and by temperature. As above, wash stringency can be increased by decreasing salt concentration or by increasing temperature. For example, stringent salt concentration for the wash steps will preferably be less than about 30 mM NaCl and 3 mM trisodium citrate, and most preferably less than about 15 mM NaCl and 1.5 mM trisodium citrate. Stringent temperature conditions 20 for the wash steps will ordinarily include a temperature of at least about 25° C, more preferably of at least about 42° C, and even more preferably of at least about 68° C. In an embodiment, wash steps will occur at 25° C in 30 mM NaCl, 3 mM trisodium citrate, and 0.1% SDS. In a more preferred embodiment, wash steps will occur at 42 C in 15 mM NaCl, 1.5 mM trisodium citrate, and 0.1% SDS. In a more preferred embodiment, wash steps will 25 occur at 68° C in 15 mM NaCl, 1.5 mM trisodium citrate, and 0.1% SDS. Additional variations on these conditions will be readily apparent to those skilled in the art. Hybridization techniques are well known to those skilled in the art and are described, for example, in Benton and Davis (Science 196:180, 1977); Grunstein and Hogness (Proc. Natl. Acad. Sci., USA 72:3961, 1975); Ausubel et al. (Current Protocols in Molecular Biology, 30 Wiley Interscience, New York, 2001); Berger and Kimmel (Guide to Molecular Cloning Techniques, 1987, Academic Press, New York); and Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, New York. By “split” is meant divided into two or more fragments. 2020221355   24 Feb 2026 A "split Cas9 protein" or "split Cas9" refers to a Cas9 protein that is provided as an N-terminal fragment and a C-terminal fragment encoded by two separate nucleotide sequences. The polypeptides corresponding to the N-terminal portion and the C-terminal portion of the Cas9 protein may be spliced to form a “reconstituted” Cas9 protein. In particular 5 embodiments, the Cas9 protein is divided into two fragments within a disordered region of the protein, e.g., as described in Nishimasu et al., Cell, Volume 156, Issue 5, pp. 935-949, 2014, or as described in Jiang et al. (2016) Science 351: 867-871. PDB file: 5F9R, each of which is incorporated herein by reference. In some embodiments, the protein is divided into two fragments at any C, T, A, or S within a region of SpCas9 between about amino acids 10   A292-G364, F445-K483, or E565-T637, or at corresponding positions in any other Cas9, Cas9 variant (e.g., nCas9, dCas9), or other napDNAbp. In some embodiments, protein is divided into two fragments at SpCas9 T310, T313, A456, S469, or C574. In some embodiments, the process of dividing the protein into two fragments is referred to as “splitting” the protein. 15          In other embodiments, the N-terminal portion of the Cas9 protein comprises amino acids 1-573 or 1-637 S. pyogenes Cas9 wild-type (SpCas9) (NCBI Reference Sequence: NC_002737.2, Uniprot Reference Sequence: Q99ZW2) and the C-terminal portion of the Cas9 protein comprises a portion of amino acids 574-1368 or 638-1368 of SpCas9 wild-type, or a corresponding position thereof. 20          The C-terminal portion of the split Cas9 can be joined with the N-terminal portion of the split Cas9 to form a complete Cas9 protein. In some embodiments, the C-terminal portion of the Cas9 protein starts from where the N-terminal portion of the Cas9 protein ends. As such, in some embodiments, the C-terminal portion of the split Cas9 comprises a portion of amino acids (551-651)-1368 of spCas9. "(551-651)-1368" means starting at an amino acid 25 between amino acids 551-651 (inclusive) and ending at amino acid 1368. For example, the C-terminal portion of the split Cas9 may comprise a portion of any one of amino acid 551-1368, 552-1368, 553-1368, 554-1368, 555-1368, 556-1368, 557-1368, 558-1368, 559-1368, 5601368, 561-1368, 562-1368, 563-1368, 564-1368, 565-1368, 566-1368, 567-1368, 568-1368, 569-1368, 570-1368, 571-1368, 572-1368, 573-1368, 574-1368, 575-1368, 576-1368, 577 30   1368, 578-1368, 579-1368, 580-1368, 581-1368, 582-1368, 583-1368, 584-1368, 585-1368, 586-1368, 587-1368, 588-1368, 589-1368, 590-1368, 591-1368, 592-1368, 593-1368, 5941368, 595-1368, 596-1368, 597-1368, 598-1368, 599-1368, 600-1368, 601-1368, 602-1368, 603-1368, 604-1368, 605-1368, 606-1368, 607-1368, 608-1368, 609-1368, 610-1368, 611- 2020221355   24 Feb 2026 1368, 612-1368, 613-1368, 614-1368, 615-1368, 616-1368, 617-1368, 618-1368, 619-1368, 620-1368, 621-1368, 622-1368, 623-1368, 624-1368, 625-1368, 626-1368, 627-1368, 6281368, 629-1368, 630-1368, 631-1368, 632-1368, 633-1368, 634-1368, 635-1368, 636-1368, 637-1368, 638-1368, 639-1368, 640-1368, 641-1368, 642-1368, 643-1368, 644-1368, 645 5   1368, 646-1368, 647-1368, 648-1368, 649-1368, 650-1368, or 651-1368 of spCas9. In some embodiments, the C-terminal portion of the split Cas9 protein comprises a portion of amino acids 574-1368 or 638-1368 of SpCas9. By "subject" is meant a mammal, including, but not limited to, a human or nonhuman mammal, such as a bovine, equine, canine, ovine, or feline. Subjects include 10 livestock, domesticated animals raised to produce labor and to provide commodities, such as food, including without limitation, cattle, goats, chickens, horses, pigs, rabbits, and sheep. By "substantially identical" is meant a polypeptide or nucleic acid molecule exhibiting at least 50% identity to a reference amino acid sequence (for example, any one of the amino acid sequences described herein) or nucleic acid sequence (for example, any one of 15 the nucleic acid sequences described herein). In one embodiment, such a sequence is at least 60%, 80% or 85%, 90%, 95% or even 99% identical at the amino acid level or nucleic acid to the sequence used for comparison. Sequence identity is typically measured using sequence analysis software (for example, Sequence Analysis Software Package of the Genetics Computer Group, University 20 of Wisconsin Biotechnology Center, 1710 University Avenue, Madison, Wis. 53705, BLAST, BESTFIT, COBALT, EMBOSS Needle, GAP, or PILEUP / PRETTYBOX programs). Such software matches identical or similar sequences by assigning degrees of homology to various substitutions, deletions, and / or other modifications. Conservative substitutions typically include substitutions within the following groups: glycine, alanine; 25 valine, isoleucine, leucine; aspartic acid, glutamic acid, asparagine, glutamine; serine, threonine; lysine, arginine; and phenylalanine, tyrosine. In an exemplary approach to determining the degree of identity, a BLAST program may be used, with a probability score between e-3 and e-100 indicating a closely related sequence. COBALT is used, for example, with the following parameters: 30          a) alignment parameters: Gap penalties-11,-1 and End-Gap penalties-5,-1, b) CDD Parameters: Use RPS BLAST on; Blast E-value 0.003; Find Conserved columns and Recompute on, and 2020221355   24 Feb 2026 c) Query Clustering Parameters: Use query clusters on; Word Size 4; Max cluster distance 0.8; Alphabet Regular. EMBOSS Needle is used, for example, with the following parameters: 10 a) b) c) d) e) f) g) Matrix: BLOSUM62; GAP OPEN: 10; GAP EXTEND: 0.5; OUTPUT FORMAT: pair; END GAP PENALTY: false; END GAP OPEN: 10; and END GAP EXTEND: 0.5. The term "target site" refers to a sequence within a nucleic acid molecule that is modified by a nucleobase editor. In one embodiment, the target site is deaminated by a deaminase or a fusion protein comprising a deaminase (e.g., adenine deaminase). As used herein, the terms “treat,” treating,” “treatment,” and the like refer to reducing 15 or ameliorating a disorder and / or symptom associated therewith or obtaining a desired pharmacologic and / or physiologic effect. It will be appreciated that, although not precluded, treating a disorder or condition does not require that the disorder, condition or symptoms associated therewith be completely eliminated. In some embodiments, the effect is therapeutic, i.e., without limitation, the effect partially or completely reduces, diminishes, 20 abrogates, abates, alleviates, decreases the intensity of, or cures a disease and / or adverse symptom attributable to the disease. In some embodiments, the effect is preventative, i.e., the effect protects or prevents an occurrence or reoccurrence of a disease or condition. To this end, the presently disclosed methods comprise administering a therapeutically effective amount of a compositions as described herein. 25          By “uracil glycosylase inhibitor” or “UGI” is meant an agent that inhibits the uracil- excision repair system. In one embodiment, the agent is a protein or fragment thereof that binds a host uracil-DNA glycosylase and prevents removal of uracil residues from DNA. In an embodiment, a UGI is a protein, a fragment thereof, or a domain that is capable of inhibiting a uracil-DNA glycosylase base-excision repair enzyme. In some embodiments, a 30 UGI domain comprises a wild-type UGI or a modified version thereof. In some embodiments, a UGI domain comprises a fragment of the exemplary amino acid sequence set forth below. In some embodiments, a UGI fragment comprises an amino acid sequence that comprises at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at 2020221355   24 Feb 2026 least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% of the exemplary UGI sequence provided below. In some embodiments, a UGI comprises an amino acid sequence that is homologous to the exemplary UGI amino acid sequence or fragment thereof, as set forth below. In some embodiments, the UGI, or a portion thereof, is at least 5   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%, at least 99%, at least 99.5%, at least 99.9%, or 100% identical to a wildtype UGI or a UGI sequence, or portion thereof, as set forth below. An exemplary UGI comprises an amino acid sequence as follows: >splP14739IUNGI_BPPB2 Uracil-DNA glycosylase inhibitor 10 MTNLSDIIEKETGKQLVIQESILMLPEEVEEVIGNKPESDILVHTAYDESTDENVMLLTSD APEYKPWALVIQDSNGENKIKML. The term “vector” refers to a means of introducing a nucleic acid sequence into a cell, resulting in a transformed cell. Vectors include plasmids, transposons, phages, viruses, liposomes, and episome. “Expression vectors” are nucleic acid sequences comprising the 15 nucleotide sequence to be expressed in the recipient cell. Expression vectors may include additional nucleic acid sequences to promote and / or facilitate the expression of the of the introduced sequence such as start, stop, enhancer, promoter, and secretion sequences. Any compositions or methods provided herein can be combined with one or more of any of the other compositions and methods provided herein. 20           DNA editing has emerged as a viable means to modify disease states by correcting pathogenic mutations at the genetic level. Until recently, all DNA editing platforms have functioned by inducing a DNA double strand break (DSB) at a specified genomic site and relying on endogenous DNA repair pathways to determine the product outcome in a semistochastic manner, resulting in complex populations of genetic products. Though precise, 25 user-defined repair outcomes can be achieved through the homology directed repair (HDR) pathway, a number of challenges have prevented high efficiency repair using HDR in therapeutically-relevant cell types. In practice, this pathway is inefficient relative to the competing, error-prone non-homologous end joining pathway. Further, HDR is tightly restricted to the G1 and S phases of the cell cycle, preventing precise repair of DSBs in post- 30 mitotic cells. As a result, it has proven difficult or impossible to alter genomic sequences in a user-defined, programmable manner with high efficiencies in these populations. BRIEF DESCRIPTION OF THE DRAWINGS 2020221355   24 Feb 2026 The features of the present disclosure are set forth with particularity herein. A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the disclosure are utilized, and the accompanying drawings of which: 5          FIG. 1 depicts a G6PC nucleotide target sequence and corresponding amino acid sequence indicating bystander and on target A > G bases for correction of the GSD1a Q347X mutation. FIG. 2 depicts precise base correction and bystander editing. FIG. 2A depicts positions of a target nucleobase and a bystander nucleobase. FIG. 2B depicts the percentage 10 of precise on target and bystander correction of the GSD1a G6PC Q347X mutation in HEK293T cells using ABE8 variants. FIGS. 3A and 3B depict editor optimization for correction of the GSD1a G6PC Q347X mutation in HEK293T cells. FIG. 3A depicts a G6PC nucleotide target sequence and corresponding amino acid sequence indicating bystander and on target A > G bases and the 15 GGA PAM sequence for correction of the GSD1a Q347X mutation. FIG. 3B is a graph depicting the percentage of correction of the GSD1a G6PC Q347X mutation using ABE8 monomer and heterodimer variants. FIG. 4 is a graph depicting the percentage of correction of the GSD1a G6PC Q347X mutation using ABE8 double mutant variants in HEK293T cells comparing bystander (A2) 20 and on target (A6) A > G bases. FIG. 5 is a graph depicting the percentage of precise correction of the GSD1a Q347X mutation using ABE8 variants in patient derived B-lymphocytes. FIGS. 6A and 6B depict precise correction of GSD1a G6PC Q347X mutation in compound heterozygous (Q347X, G222R) patient iPS-derived hepatocytes. FIG. 6A depicts 25 a G6PC nucleotide target sequence, corresponding amino acid sequence, and the GGA PAM sequence indicating bystander and on target A > G bases for correction of the GSD1a Q347X mutation. FIG. 6B is a graph depicting the A > G base editing efficiency of the GSD1a Q347X mutation using an ABE8 variant comparing on-target to bystander correction. FIGS. 7A and 7B depict editor optimization for correction of GSD1a Q347X 30 mutation in patient iPS-derived hepatocytes. FIG. 7A shows the NGA PAM sequence and corresponding target sequence for GSD1a indicating bystander and on target A > G bases. FIG. 7B is a graph depicting the base editing efficiency of the GSD1a Q347X mutation using ABE8 variants. 2020221355   24 Feb 2026 FIGS. 8A and 8B provide an in vitro transduction schedule for the GSD1a Q347X mutation in a primary hepatocyte co-cultures system. FIG. 8A provides a timeline of the in vitro transduction schedule in either hepatocyte monolayers or hepatocyte co-cultures showing representative time points. FIG. 8B shows images of transduced primary 5 hepatocytes from donors used in the co-culture system for the GSD1a Q347X mutation. FIG. 9 shows images of GFP expression (GFP, Brightfield, Merge) on day 6 (D6) in primary hepatocyte co-cultured cells transduced with lentiviral vector containing the GSD1a Q347X mutation at a multiplicity of infection (MOI) of 30, 100, and 300 lentivirus. FIGS. 10A, 10B, and 10C depict the correction of the GSD1a Q347X mutation in 10 lentiviral transduced primary hepatocyte co-cultures system. FIG. 10A shows an image of GFP expression in primary hepatocyte co-cultured cells (donor RSE) transduced with lentiviral vector containing the GSD1a Q347X mutation at a MOI of 500. FIG. 10B is a graph depicting the A > G base editing efficiency for on-target correction of the GSD1a Q347X mutation and indels in transduced primary hepatocyte co-cultures. The dashed line 15 represents the A > G base editing efficiency for therapeutic benefit. FIG. 10C is a graph depicting the A > G base editing efficiency of the GSD1a Q347X mutation in transduced primary hepatocyte co-cultures in media with or without polyethylene glycol 8000 (PEG8K) and treated with collagenase Types III, IV, and hyaluronic acid or were kept untreated. FIG. 11 depicts a G6PC nucleotide target sequence and corresponding amino acid 20 sequence indicating bystander and on target A > G bases for correction of the GSD1a R83C mutation. FIGS. 12A and 12B depict precise correction of GSD1a G6PC R83C mutation in HEK293T cells. FIG. 12A depicts a G6PC nucleotide target sequence and corresponding amino acid sequence indicating bystander, synonymous, and on target A > G bases for 25 correction of the GSD1a R83C mutation. FIG. 12B is a graph depicting the A > G base editing efficiency of the GSD1a R83C mutation using ABE8 variants comparing on-target to bystander correction. FIGS. 13A and 13B depict base editing of G6PC R83C mutation by plasmid transfection in HEK293T lenti-model cells. FIG. 13A shows the GAGAAT PAM sequence 30 and corresponding target sequence for GSD1a gRNA# 820 and the AGA PAM sequence and corresponding target sequence for GSD1a gRNA# 1121, indicating bystander and on target A > G bases of the target sequence. FIG. 13B is a graph depicting the percentage of on target 2020221355   24 Feb 2026 and bystander correction of the GSD1a R83C mutation using ABE base editors with gRNA1121 or gRNA820. FIG. 14 is a graph depicting the A > G base editing efficiency of the GSD1a R83C mutation using saABE8 variants. 5          FIG. 15 is a graph depicting the A > G base editing efficiency of the GSD1a R83C mutation using saABE8 double mutant variants. FIG. 16 is a graph depicting the A > G base editing efficiency of on target, bystander, and synonymous bystander corrections of the GSD1a R83C mutation using ABE8 variants in HEK293T cells. 10         FIGS. 17A and 17B depict the correction of the GSD1a Q347X mutation in primary mouse hepatocytes isolated from a transgenic mouse model for GSD1a. FIG. 17A shows an image of primary mouse hepatocytes isolated from ASC transgenic mouse model, huG6PC, R83C (V166L). FIG. 17B is a graph depicting the base editing efficiency of positions A12G, A10G, A6G, and Indels for correction of the GSD1a R83C mutation in primary mouse 15 hepatocytes isolated from a GSD1a transgenic mouse model using ABE8 variants. FIG. 18 is a graph depicting levels of A>G base editing at on-target (12A) and off-target (6A) sites using a TadA-SaCas9 ABE editor in combination with guide RNAs of varying lengths as shown. Data were obtained in HEK293T cells. Target site and other editing details are also provided. 20          FIG. 19 is a graph depicting levels of A>G base editing (Percent Editing) at on-target (12A) and off-target (6A) sites using ABE8s (TadA*8 variants-SaCas9) in combination with 20nt and 21nt guide RNAs. Data were obtained in HEK293T cells. FIG. 20 is a graph depicting levels of A>G base editing (% Correction of R83C) at on-target (12A) and off-target (6A) sites using ABE base editors (TadA variants-SaCas9) in 25 combination with 20nt or 21nt guide RNAs. Data were obtained in HEK293T cells. FIG. 21 is a graph depicting levels of A>G (%) base editing at on-target (12A) and off-target (6A) sites using ABE base editors (TadA variants-SaCas9) in combination with 20nt or 21nt guide RNAs. Data were obtained in primary human hepatocyte lentiviral model for GSD1a R83C. 30          FIG. 22 is a graph depicting levels of A>G base editing (% Correction of R83C) at on-target (12A) and off-target (6A) sites using ABE base editors (TadA variants-SaCas9) in combination with 20nt or 21nt guide RNAs. Data were obtained in primary human hepatocyte lentiviral model for GSD1a R83C. 2020221355   24 Feb 2026 FIG. 23 is a graph depicting levels of A>G (%) precise base editing at on-target and off-target sites in heterozygous transgenic GSD1a R83C mice. FIG. 24 is a table depicting Cas9 variants for accessing all possible PAMs for NRNN PAM. Only Cas9 variants that require recognition of three or fewer defined nucleotides in 5 their PAMs are listed. The non-G PAM variants include SpCas9-NRRH, SpCas9-NRTH, and SpCas9-NRCH. DETAILED DESCRIPTION The disclosure provides compositions comprising novel adenosine base editors (e.g., 10 ABE8) that have increased efficiency and methods of using base editors comprising adenosine deaminase variants for altering mutations associated with Glycogen Storage Disease Type 1a (GSD1a). The disclosure is based, at least in part, on the discovery that a base editor featuring adenosine deaminase variants (i.e. ABE8) precisely corrects single nucleotide polymorphisms 15 in the endogenous glucose-6-phosphatase (G6PC) gene (e.g. R83C, Q347X). The GSDla mutations, R83C and Q347X, are cytidine to thymidine (C^T) transition mutations, resulting in a C^G to T»A base pair substitution. These substitutions may be reverted back to a wild-type, non-pathogenic genomic sequence with an adenosine base editor (ABE) which catalyzes A»T to G»C substitutions. By extension, GSD1a-causing 20 mutations are potential targets for reversion to wild-type sequence using ABEs without the risks of inducing G6PC gene overexpression, as may occur using gene therapy. Accordingly, A»T to G*C DNA base editing precisely corrects one or more of the most prevalent GSD1a-causing mutations in the G6PC gene. 25 NUCLEOBASE EDITOR Disclosed herein is a base editor or a nucleobase editor for editing, modifying or altering a target nucleotide sequence of a polynucleotide. Described herein is a nucleobase editor or a base editor comprising a polynucleotide programmable nucleotide binding domain and a nucleobase editing domain (e.g., adenosine deaminase). A polynucleotide 30 programmable nucleotide binding domain, when in conjunction with a bound guide polynucleotide (e.g., gRNA), can specifically bind to a target polynucleotide sequence (i.e., via complementary base pairing between bases of the bound guide nucleic acid and bases of the target polynucleotide sequence) and thereby localize the base editor to the target nucleic 2020221355   24 Feb 2026 acid sequence desired to be edited. In some embodiments, the target polynucleotide sequence comprises single-stranded DNA or double-stranded DNA. In some embodiments, the target polynucleotide sequence comprises RNA. In some embodiments, the target polynucleotide sequence comprises a DNA-RNA hybrid. 5 Polynucleotide Programmable Nucleotide Binding Domain It should be appreciated that polynucleotide programmable nucleotide binding domains can also include nucleic acid programmable proteins that bind RNA. For example, the polynucleotide programmable nucleotide binding domain can be associated with a nucleic 10 acid that guides the polynucleotide programmable nucleotide binding domain to an RNA. Other nucleic acid programmable DNA binding proteins are also within the scope of this disclosure, though they are not specifically listed in this disclosure. A polynucleotide programmable nucleotide binding domain of a base editor can itself comprise one or more domains. For example, a polynucleotide programmable nucleotide 15 binding domain can comprise one or more nuclease domains. In some embodiments, the nuclease domain of a polynucleotide programmable nucleotide binding domain can comprise an endonuclease or an exonuclease. Herein the term “exonuclease” refers to a protein or polypeptide capable of digesting a nucleic acid (e.g., RNA or DNA) from free ends, and the term “endonuclease” refers to a protein or polypeptide capable of catalyzing (e.g., cleaving) 20 internal regions in a nucleic acid (e.g., DNA or RNA). In some embodiments, an endonuclease can cleave a single strand of a double-stranded nucleic acid. In some embodiments, an endonuclease can cleave both strands of a double-stranded nucleic acid molecule. In some embodiments a polynucleotide programmable nucleotide binding domain can be a deoxyribonuclease. In some embodiments a polynucleotide programmable 25 nucleotide binding domain can be a ribonuclease. In some embodiments, a nuclease domain of a polynucleotide programmable nucleotide binding domain can cut zero, one, or two strands of a target polynucleotide. In some embodiments, the polynucleotide programmable nucleotide binding domain can comprise a nickase domain. Herein the term “nickase” refers to a polynucleotide 30 programmable nucleotide binding domain comprising a nuclease domain that is capable of cleaving only one strand of the two strands in a duplexed nucleic acid molecule (e.g., DNA). In some embodiments, a nickase can be derived from a fully catalytically active (e.g., natural) form of a polynucleotide programmable nucleotide binding domain by introducing one or 2020221355   24 Feb 2026 more mutations into the active polynucleotide programmable nucleotide binding domain. For example, where a polynucleotide programmable nucleotide binding domain comprises a nickase domain derived from Cas9, the Cas9-derived nickase domain can include a D10A mutation and a histidine at position 840. In such embodiments, the residue H840 retains 5   catalytic activity and can thereby cleave a single strand of the nucleic acid duplex. In another example, a Cas9-derived nickase domain can comprise an H840A mutation, while the amino acid residue at position 10 remains a D. In some embodiments, a nickase can be derived from a fully catalytically active (e.g., natural) form of a polynucleotide programmable nucleotide binding domain by removing all or a portion of a nuclease domain that is not 10 required for the nickase activity. For example, where a polynucleotide programmable nucleotide binding domain comprises a nickase domain derived from Cas9, the Cas9-derived nickase domain can comprise a deletion of all or a portion of the RuvC domain or the HNH domain. The amino acid sequence of an exemplary catalytically active Cas9 is as follows: 15 MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT 20 EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV 25 LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH 30 VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS 2020221355   24 Feb 2026 HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD. A base editor comprising a polynucleotide programmable nucleotide binding domain 5 comprising a nickase domain is thus able to generate a single-strand DNA break (nick) at a specific polynucleotide target sequence (e.g., determined by the complementary sequence of a bound guide nucleic acid). In some embodiments, the strand of a nucleic acid duplex target polynucleotide sequence that is cleaved by a base editor comprising a nickase domain (e.g., Cas9-derived nickase domain) is the strand that is not edited by the base editor (i.e., the 10 strand that is cleaved by the base editor is opposite to a strand comprising a base to be edited). In other embodiments, a base editor comprising a nickase domain (e.g., Cas9-derived nickase domain) can cleave the strand of a DNA molecule which is being targeted for editing. In such embodiments, the non-targeted strand is not cleaved. Also provided herein are base editors comprising a polynucleotide programmable 15 nucleotide binding domain which is catalytically dead (i.e., incapable of cleaving a target polynucleotide sequence). Herein the terms “catalytically dead” and “nuclease dead” are used interchangeably to refer to a polynucleotide programmable nucleotide binding domain which has one or more mutations and / or deletions resulting in its inability to cleave a strand of a nucleic acid. In some embodiments, a catalytically dead polynucleotide programmable 20 nucleotide binding domain base editor can lack nuclease activity as a result of specific point mutations in one or more nuclease domains. For example, in the case of a base editor comprising a Cas9 domain, the Cas9 can comprise both a D10A mutation and an H840A mutation. Such mutations inactivate both nuclease domains, thereby resulting in the loss of nuclease activity. In other embodiments, a catalytically dead polynucleotide programmable 25 nucleotide binding domain can comprise one or more deletions of all or a portion of a catalytic domain (e.g., RuvC1 and / or HNH domains). In further embodiments, a catalytically dead polynucleotide programmable nucleotide binding domain comprises a point mutation (e.g., D10A or H840A) as well as a deletion of all or a portion of a nuclease domain. Also contemplated herein are mutations capable of generating a catalytically dead 30 polynucleotide programmable nucleotide binding domain from a previously functional version of the polynucleotide programmable nucleotide binding domain. For example, in the case of catalytically dead Cas9 (“dCas9”), variants having mutations other than D10A and H840A are provided, which result in nuclease inactivated Cas9. Such mutations, by way of 2020221355   24 Feb 2026 example, include other amino acid substitutions at D10 and H840, or other substitutions within the nuclease domains of Cas9 (e.g., substitutions in the HNH nuclease subdomain and / or the RuvC1 subdomain). Additional suitable nuclease-inactive dCas9 domains can be apparent to those of skill in the art based on this disclosure and knowledge in the field, and 5 are within the scope of this disclosure. Such additional exemplary suitable nuclease-inactive Cas9 domains include, but are not limited to, D10A / H840A, D10A / D839A / H840A, and D10A / D839A / H840A / N863A mutant domains (See, e.g., Prashant et al., CAS9 transcriptional activators for target specificity screening and paired nickases for cooperative genome engineering. Nature Biotechnology. 2013; 31(9): 833-838, the entire contents of 10 which are incorporated herein by reference). Non-limiting examples of a polynucleotide programmable nucleotide binding domain which can be incorporated into a base editor include a CRISPR protein-derived domain, a restriction nuclease, a meganuclease, TAL nuclease (TALEN), and a zinc finger nuclease (ZFN). In some embodiments, a base editor comprises a polynucleotide programmable 15 nucleotide binding domain comprising a natural or modified protein or portion thereof which via a bound guide nucleic acid is capable of binding to a nucleic acid sequence during CRISPR (i.e., Clustered Regularly Interspaced Short Palindromic Repeats)-mediated modification of a nucleic acid. Such a protein is referred to herein as a “CRISPR protein.” Accordingly, disclosed herein is a base editor comprising a polynucleotide programmable 20 nucleotide binding domain comprising all or a portion of a CRISPR protein (i.e. a base editor comprising as a domain all or a portion of a CRISPR protein, also referred to as a “CRISPR protein-derived domain” of the base editor). A CRISPR protein-derived domain incorporated into a base editor can be modified compared to a wild-type or natural version of the CRISPR protein. For example, as described below a CRISPR protein-derived domain can comprise 25 one or more mutations, insertions, deletions, rearrangements and / or recombinations relative to a wild-type or natural version of the CRISPR protein. CRISPR is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain spacers, sequences complementary to antecedent mobile elements, and target 30 invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). In type II CRISPR systems, correct processing of pre-crRNA requires a transencoded small RNA (tracrRNA), endogenous ribonuclease 3 (rnc) and a Cas9 protein. The tracrRNA serves as a guide for ribonuclease 3-aided processing of pre-crRNA. 2020221355   24 Feb 2026 Subsequently, Cas9 / crRNA / tracrRNA endonucleolytically cleaves linear or circular dsDNA target complementary to the spacer. The target strand not complementary to crRNA is first cut endonucleolytically, and then trimmed 3'-5‘ exonucleolytically. In nature, DNA-binding and cleavage typically requires protein and both RNAs. However, single guide RNAs 5 (“sgRNA,” or simply “gRNA”) can be engineered so as to incorporate aspects of both the crRNA and tracrRNA into a single RNA species. See, e.g., Jinek M., Chylinski K., Fonfara I., Hauer M., Doudna J. A., Charpentier E. Science 337:816-821(2012), the entire contents of which is hereby incorporated by reference. Cas9 recognizes a short motif in the CRISPR repeat sequences (the PAM or protospacer adjacent motif) to help distinguish self versus non- 10 self. In some embodiments, the methods described herein can utilize an engineered Cas protein. A guide RNA (gRNA) is a short synthetic RNA composed of a scaffold sequence necessary for Cas-binding and a user-defined ~20 nucleotide spacer that defines the genomic target to be modified. Thus, a skilled artisan can change the genomic target of the Cas 15 protein specificity is partially determined by how specific the gRNA targeting sequence is for the genomic target compared to the rest of the genome. In some embodiments, the gRNA scaffold sequence is as follows: GUUUUAGAGC UAGAAAUAGC AAGUUAAAAU AAGGCUAGUC CGUUAUCAAC UUGAAAAAGU GGCACCGAGU CGGUGCUUUU. 20          In some embodiments, a CRISPR protein-derived domain incorporated into a base editor is an endonuclease (e.g., deoxyribonuclease or ribonuclease) capable of binding a target polynucleotide when in conjunction with a bound guide nucleic acid. In some embodiments, a CRISPR protein-derived domain incorporated into a base editor is a nickase capable of binding a target polynucleotide when in conjunction with a bound guide nucleic 25 acid. In some embodiments, a CRISPR protein-derived domain incorporated into a base editor is a catalytically dead domain capable of binding a target polynucleotide when in conjunction with a bound guide nucleic acid. In some embodiments, a target polynucleotide bound by a CRISPR protein derived domain of a base editor is DNA. In some embodiments, a target polynucleotide bound by a CRISPR protein-derived domain of a base editor is RNA. 30          Cas proteins that can be used herein include class 1 and class 2. Non-limiting examples of Cas proteins include Cas1, Cas1B, Cas2, Cas3, Cas4, Cas5, Cas5d, Cas5t, Cas5h, Cas5a, Cas6, Cas7, Cas8, Cas9 (also known as Csn1 or Csx12), Cas10, Csy1 , Csy2, Csy3, Csy4, Cse1, Cse2, Cse3, Cse4, Cse5e, Csc1, Csc2, Csa5, Csn1, Csn2, Csm1, Csm2, 2020221355   24 Feb 2026 Csm3, Csm4, Csm5, Csm6, Cmr1, Cmr3, Cmr4, Cmr5, Cmr6, Csb1, Csb2, Csb3, Csx17, Csx14, Csx10, Csx16, CsaX, Csx3, Csx1, Csx1S, Csf1, Csf2, CsO, Csf4, Csd1, Csd2, Cst1, Cst2, Csh1, Csh2, Csa1, Csa2, Csa3, Csa4, Csa5, Cas12a / Cpf1, Cas12b / C2c1, Cas12c / C2c3, Cas12d / CasY, Cas12e / CasX, Cas12g, Cas12h, and Cas12i, CARF, DinG, homologues 5 thereof, or modified versions thereof. An unmodified CRISPR enzyme can have DNA cleavage activity, such as Cas9, which has two functional endonuclease domains: RuvC and HNH. A CRISPR enzyme can direct cleavage of one or both strands at a target sequence, such as within a target sequence and / or within a complement of a target sequence. For example, a CRISPR enzyme can direct cleavage of one or both strands within about 1, 2, 3, 4, 10    5, 6, 7, 8, 9, 10, 15, 20, 25, 50, 100, 200, 500, or more base pairs from the first or last nucleotide of a target sequence. A vector that encodes a CRISPR enzyme that is mutated to with respect, to a corresponding wild-type enzyme such that the mutated CRISPR enzyme lacks the ability to cleave one or both strands of a target polynucleotide containing a target sequence can be 15 used. Cas9 can refer to a polypeptide with at least or at least about 50%, 60%, 70%, 80%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity and / or sequence homology to a wild-type exemplary Cas9 polypeptide (e.g., Cas9 from S. pyogenes). Cas9 can refer to a polypeptide with at most or at most about 50%, 60%, 70%, 80%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity 20 and / or sequence homology to a wild-type exemplary Cas9 polypeptide (e.g., from S. pyogenes). Cas9 can refer to the wild-type or a modified form of the Cas9 protein that can comprise an amino acid change such as a deletion, insertion, substitution, variant, mutation, fusion, chimera, or any combination thereof. In some embodiments, a CRISPR protein-derived domain of a base editor can include 25 all or a portion of Cas9 from Corynebacterium ulcerans (NCBI Refs: NC_015683.1, NC_017317.1); Corynebacterium diphtheria (NCBI Refs: NC_016782.1, NC_016786.1); Spiroplasma syrphidicola (NCBI Ref: NC_021284.1); Prevotella intermedia (NCBI Ref: NC_017861.1); Spiroplasma taiwanense (NCBI Ref: NC_021846.1); Streptococcus iniae (NCBI Ref: NC_021314.1); Belliella baltica (NCBI Ref: NC_018010.1); Psychroflexus 30 torquis (NCBI Ref: NC_018721.1); Streptococcus thermophilus (NCBI Ref: YP_820832.1); Listeria innocua (NCBI Ref: NP_472073.1); Campylobacter jejuni (NCBI Ref: YP_002344900.1); Neisseria meningitidis (NCBI Ref: YP_002342100.1), Streptococcus pyogenes, or Staphylococcus aureus. 2020221355   24 Feb 2026 Cas9 domains of Nucleobase Editors Cas9 nuclease sequences and structures are well known to those of skill in the art (See, e.g., “Complete genome sequence of an Ml strain of Streptococcus pyogenes.” Ferretti 5 et al., J.J., McShan W.M., Ajdic D.J., Savic D.J., Savic G., Lyon K., Primeaux C, Sezate S., Suvorov A.N., Kenton S., Lai H.S., Lin S.P., Qian Y., Jia H.G., Najar F.Z., Ren Q., Zhu H., Song L., White J., Yuan X., Clifton S.W., Roe B.A., McLaughlin R.E., Proc. Natl. Acad. Sci. U.S.A. 98:4658-4663(2001); “CRISPR RNA maturation by trans-encoded small RNA and host factor RNase III.” Deltcheva E., Chylinski K., Sharma C.M., Gonzales K., Chao Y., 10 Pirzada Z.A., Eckert M.R., Vogel J., Charpentier E., Nature 471:602-607(2011); and “A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity.” Jinek M., Chylinski K., Fonfara I., Hauer M., Doudna J.A., Charpentier E. Science 337:816-821(2012), the entire contents of each of which are incorporated herein by reference). Cas9 orthologs have been described in various species, including, but not limited to, S. pyogenes 15 and S. thermophilus. Additional suitable Cas9 nucleases and sequences will be apparent to those of skill in the art based on this disclosure, and such Cas9 nucleases and sequences include Cas9 sequences from the organisms and loci disclosed in Chylinski, Rhun, and Charpentier, “The tracrRNA and Cas9 families of type II CRISPR-Cas immunity systems” (2013) RNA Biology 10:5, 726-737; the entire contents of which are incorporated herein by 20 reference. In some embodiments, a nucleic acid programmable DNA binding protein (napDNAbp) is a Cas9 domain. Non-limiting, exemplary Cas9 domains are provided herein. The Cas9 domain may be a nuclease active Cas9 domain, a nuclease inactive Cas9 domain (dCas9), or a Cas9 nickase (nCas9). In some embodiments, the Cas9 domain is a nuclease 25 active domain. For example, the Cas9 domain may be a Cas9 domain that cuts both strands of a duplexed nucleic acid (e.g., both strands of a duplexed DNA molecule). In some embodiments, the Cas9 domain comprises any one of the amino acid sequences as set forth herein. In some embodiments the Cas9 domain comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at 30 least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the amino acid sequences set forth herein. In some embodiments, the Cas9 domain comprises an amino acid sequence that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 21, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 2020221355   24 Feb 2026 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 or more mutations compared to any one of the amino acid sequences set forth herein. In some embodiments, the Cas9 domain comprises an amino acid sequence that has at least 10, at least 15, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 150, at least 200, at least 250, 5 at least 300, at least 350, at least 400, at least 500, at least 600, at least 700, at least 800, at least 900, at least 1000, at least 1100, or at least 1200 identical contiguous amino acid residues as compared to any one of the amino acid sequences set forth herein. In some embodiments, proteins comprising fragments of Cas9 are provided. For example, in some embodiments, a protein comprises one of two Cas9 domains: (1) the gRNA 10 binding domain of Cas9; or (2) the DNA cleavage domain of Cas9. In some embodiments, proteins comprising Cas9 or fragments thereof are referred to as “Cas9 variants.” A Cas9 variant shares homology to Cas9, or a fragment thereof. For example, a Cas9 variant is at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 96% identical, at least about 97% identical, at least about 15   98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical to wild-type Cas9. In some embodiments, the Cas9 variant may have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 21, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 or more amino acid changes compared to wild-type Cas9. In some embodiments, the Cas9 variant comprises a 20 fragment of Cas9 (e.g., a gRNA binding domain or a DNA-cleavage domain), such that the fragment is at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 96% identical, at least about 97% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical to the corresponding fragment of wild-type Cas9. 25 In some embodiments, the fragment is 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% identical, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% of the amino acid length of a corresponding wild-type Cas9. In some embodiments, the fragment is at least 100 amino acids in length. In some 30 embodiments, the fragment is at least 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, or at least 1300 amino acids in length. 2020221355   24 Feb 2026 In some embodiments, Cas9 fusion proteins as provided herein comprise the full-length amino acid sequence of a Cas9 protein, e.g., one of the Cas9 sequences provided herein. In other embodiments, however, fusion proteins as provided herein do not comprise a full-length Cas9 sequence, but only one or more fragments thereof. Exemplary amino acid sequences of 5 suitable Cas9 domains and Cas9 fragments are provided herein, and additional suitable sequences of Cas9 domains and fragments will be apparent to those of skill in the art. A Cas9 protein can associate with a guide RNA that guides the Cas9 protein to a specific DNA sequence that has complementary to the guide RNA. In some embodiments, the polynucleotide programmable nucleotide binding domain is a Cas9 domain, for example a 10 nuclease active Cas9, a Cas9 nickase (nCas9), or a nuclease inactive Cas9 (dCas9). Examples of nucleic acid programmable DNA binding proteins include, without limitation, Cas9 (e.g., dCas9 and nCas9), CasX, CasY, Cpf1, Cas12b / C2c1, and Cas12c / C2c3. In some embodiments, wild-type Cas9 corresponds to Cas9 from Streptococcus pyogenes (NCBI Reference Sequence: NC_017053.1, nucleotide and amino acid sequences as follows). 15 ATGGATAAGAAATACTCAATAGGCTTAGATATCGGCACAAATAGCGTCGGATGGGCGGTGAT CACTGATGATTATAAGGTTCCGTCTAAAAAGTTCAAGGTTCTGGGAAATACAGACCGCCACA GTATCAAAAAAAATCTTATAGGGGCTCTTTTATTTGGCAGTGGAGAGACAGCGGAAGCGACT CGTCTCAAACGGACAGCTCGTAGAAGGTATACACGTCGGAAGAATCGTATTTGTTATCTACA GGAGATTTTTTCAAATGAGATGGCGAAAGTAGATGATAGTTTCTTTCATCGACTTGAAGAGT 20 CTTTTTTGGTGGAAGAAGACAAGAAGCATGAACGTCATCCTATTTTTGGAAATATAGTAGAT GAAGTTGCTTATCATGAGAAATATCCAACTATCTATCATCTGCGAAAAAAATTGGCAGATTC TACTGATAAAGCGGATTTGCGCTTAATCTATTTGGCCTTAGCGCATATGATTAAGTTTCGTG GTCATTTTTTGATTGAGGGAGATTTAAATCCTGATAATAGTGATGTGGACAAACTATTTATC CAGTTGGTACAAATCTACAATCAATTATTTGAAGAAAACCCTATTAACGCAAGTAGAGTAGA 25 TGCTAAAGCGATTCTTTCTGCACGATTGAGTAAATCAAGACGATTAGAAAATCTCATTGCTC AGCTCCCCGGTGAGAAGAGAAATGGCTTGTTTGGGAATCTCATTGCTTTGTCATTGGGATTG ACCCCTAATTTTAAATCAAATTTTGATTTGGCAGAAGATGCTAAATTACAGCTTTCAAAAGA TACTTACGATGATGATTTAGATAATTTATTGGCGCAAATTGGAGATCAATATGCTGATTTGT TTTTGGCAGCTAAGAATTTATCAGATGCTATTTTACTTTCAGATATCCTAAGAGTAAATAGT 30 GAAATAACTAAGGCTCCCCTATCAGCTTCAATGATTAAGCGCTACGATGAACATCATCAAGA CTTGACTCTTTTAAAAGCTTTAGTTCGACAACAACTTCCAGAAAAGTATAAAGAAATCTTTT TTGATCAATCAAAAAACGGATATGCAGGTTATATTGATGGGGGAGCTAGCCAAGAAGAATTT TATAAATTTATCAAACCAATTTTAGAAAAAATGGATGGTACTGAGGAATTATTGGTGAAACT AAATCGTGAAGATTTGCTGCGCAAGCAACGGACCTTTGACAACGGCTCTATTCCCCATCAAA 2020221355   24 Feb 2026 TTCACTTGGGTGAGCTGCATGCTATTTTGAGAAGACAAGAAGACTTTTATCCATTTTTAAAA GACAATCGTGAGAAGATTGAAAAAATCTTGACTTTTCGAATTCCTTATTATGTTGGTCCATT GGCGCGTGGCAATAGTCGTTTTGCATGGATGACTCGGAAGTCTGAAGAAACAATTACCCCAT GGAATTTTGAAGAAGTTGTCGATAAAGGTGCTTCAGCTCAATCATTTATTGAACGCATGACA 5 AACTTTGATAAAAATCTTCCAAATGAAAAAGTACTACCAAAACATAGTTTGCTTTATGAGTA TTTTACGGTTTATAACGAATTGACAAAGGTCAAATATGTTACTGAGGGAATGCGAAAACCAG CATTTCTTTCAGGTGAACAGAAGAAAGCCATTGTTGATTTACTCTTCAAAACAAATCGAAAA GTAACCGTTAAGCAATTAAAAGAAGATTATTTCAAAAAAATAGAATGTTTTGATAGTGTTGA AATTTCAGGAGTTGAAGATAGATTTAATGCTTCATTAGGCGCCTACCATGATTTGCTAAAAA 10 TTATTAAAGATAAAGATTTTTTGGATAATGAAGAAAATGAAGATATCTTAGAGGATATTGTT TTAACATTGACCTTATTTGAAGATAGGGGGATGATTGAGGAAAGACTTAAAACATATGCTCA CCTCTTTGATGATAAGGTGATGAAACAGCTTAAACGTCGCCGTTATACTGGTTGGGGACGTT TGTCTCGAAAATTGATTAATGGTATTAGGGATAAGCAATCTGGCAAAACAATATTAGATTTT TTGAAATCAGATGGTTTTGCCAATCGCAATTTTATGCAGCTGATCCATGATGATAGTTTGAC 15 ATTTAAAGAAGATATTCAAAAAGCACAGGTGTCTGGACAAGGCCATAGTTTACATGAACAGA TTGCTAACTTAGCTGGCAGTCCTGCTATTAAAAAAGGTATTTTACAGACTGTAAAAATTGTT GATGAACTGGTCAAAGTAATGGGGCATAAGCCAGAAAATATCGTTATTGAAATGGCACGTGA AAATCAGACAACTCAAAAGGGCCAGAAAAATTCGCGAGAGCGTATGAAACGAATCGAAGAAG GTATCAAAGAATTAGGAAGTCAGATTCTTAAAGAGCATCCTGTTGAAAATACTCAATTGCAA 20 AATGAAAAGCTCTATCTCTATTATCTACAAAATGGAAGAGACATGTATGTGGACCAAGAATT AGATATTAATCGTTTAAGTGATTATGATGTCGATCACATTGTTCCACAAAGTTTCATTAAAG ACGATTCAATAGACAATAAGGTACTAACGCGTTCTGATAAAAATCGTGGTAAATCGGATAAC GTTCCAAGTGAAGAAGTAGTCAAAAAGATGAAAAACTATTGGAGACAACTTCTAAACGCCAA GTTAATCACTCAACGTAAGTTTGATAATTTAACGAAAGCTGAACGTGGAGGTTTGAGTGAAC 25 TTGATAAAGCTGGTTTTATCAAACGCCAATTGGTTGAAACTCGCCAAATCACTAAGCATGTG GCACAAATTTTGGATAGTCGCATGAATACTAAATACGATGAAAATGATAAACTTATTCGAGA GGTTAAAGTGATTACCTTAAAATCTAAATTAGTTTCTGACTTCCGAAAAGATTTCCAATTCT ATAAAGTACGTGAGATTAACAATTACCATCATGCCCATGATGCGTATCTAAATGCCGTCGTT GGAACTGCTTTGATTAAGAAATATCCAAAACTTGAATCGGAGTTTGTCTATGGTGATTATAA 30 AGTTTATGATGTTCGTAAAATGATTGCTAAGTCTGAGCAAGAAATAGGCAAAGCAACCGCAA AATATTTCTTTTACTCTAATATCATGAACTTCTTCAAAACAGAAATTACACTTGCAAATGGA GAGATTCGCAAACGCCCTCTAATCGAAACTAATGGGGAAACTGGAGAAATTGTCTGGGATAA AGGGCGAGATTTTGCCACAGTGCGCAAAGTATTGTCCATGCCCCAAGTCAATATTGTCAAGA AAACAGAAGTACAGACAGGCGGATTCTCCAAGGAGTCAATTTTACCAAAAAGAAATTCGGAC 2020221355   24 Feb 2026 AAGCTTATTGCTCGTAAAAAAGACTGGGATCCAAAAAAATATGGTGGTTTTGATAGTCCAAC GGTAGCTTATTCAGTCCTAGTGGTTGCTAAGGTGGAAAAAGGGAAATCGAAGAAGTTAAAAT CCGTTAAAGAGTTACTAGGGATCACAATTATGGAAAGAAGTTCCTTTGAAAAAAATCCGATT GACTTTTTAGAAGCTAAAGGATATAAGGAAGTTAAAAAAGACTTAATCATTAAACTACCTAA 5 ATATAGTCTTTTTGAGTTAGAAAACGGTCGTAAACGGATGCTGGCTAGTGCCGGAGAATTAC AAAAAGGAAATGAGCTGGCTCTGCCAAGCAAATATGTGAATTTTTTATATTTAGCTAGTCAT TATGAAAAGTTGAAGGGTAGTCCAGAAGATAACGAACAAAAACAATTGTTTGTGGAGCAGCA TAAGCATTATTTAGATGAGATTATTGAGCAAATCAGTGAATTTTCTAAGCGTGTTATTTTAG CAGATGCCAATTTAGATAAAGTTCTTAGTGCATATAACAAACATAGAGACAAACCAATACGT 10 GAACAAGCAGAAAATATTATTCATTTATTTACGTTGACGAATCTTGGAGCTCCCGCTGCTTT TAAATATTTTGATACAACAATTGATCGTAAACGATATACGTCTACAAAAGAAGTTTTAGATG CCACTCTTATCCATCAATCCATCACTGGTCTTTATGAAACACGCATTGATTTGAGTCAGCTA GGAGGTGACTGA 15 MDKKYSIGLDIGTNSVGWAVITDDYKVPSKKFKVLGNTDRHSIKKNLIGALLFGSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLADSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQIYNQLFEENPINASRVDAKAILSARLSKSRRLENLIAQLPGEKRNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNS 20 EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGAYHDLLKIIKDKDFLDNEENEDILEDIV 25 LTLTLFEDRGMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGHSLHEQIANLAGSPAIKKGILQTVKIV DELVKVMGHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFIKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV 30 AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV GTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANG EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKE SIL PKRNSD KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH 2020221355   24 Feb 2026 YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL GGD (single underline: HNH domain; double underline: RuvC domain) 5          In some embodiments, wild-type Cas9 corresponds to, or comprises the following nucleotide and / or amino acid sequences: ATGGATAAAAAGTATTCTATTGGTTTAGACATCGGCACTAATTCCGTTGGATGGGCTGTCAT AACCGATGAATACAAAGTACCTTCAAAGAAATTTAAGGTGTTGGGGAACACAGACCGTCATT CGATTAAAAAGAATCTTATCGGTGCCCTCCTATTCGATAGTGGCGAAACGGCAGAGGCGACT 10 CGCCTGAAACGAACCGCTCGGAGAAGGTATACACGTCGCAAGAACCGAATATGTTACTTACA AGAAATTTTTAGCAATGAGATGGCCAAAGTTGACGATTCTTTCTTTCACCGTTTGGAAGAGT CCTTCCTTGTCGAAGAGGACAAGAAACATGAACGGCACCCCATCTTTGGAAACATAGTAGAT GAGGTGGCATATCATGAAAAGTACCCAACGATTTATCACCTCAGAAAAAAGCTAGTTGACTC AACTGATAAAGCGGACCTGAGGTTAATCTACTTGGCTCTTGCCCATATGATAAAGTTCCGTG 15 GGCACTTTCTCATTGAGGGTGATCTAAATCCGGACAACTCGGATGTCGACAAACTGTTCATC CAGTTAGTACAAACCTATAATCAGTTGTTTGAAGAGAACCCTATAAATGCAAGTGGCGTGGA TGCGAAGGCTATTCTTAGCGCCCGCCTCTCTAAATCCCGACGGCTAGAAAACCTGATCGCAC AATTACCCGGAGAGAAGAAAAATGGGTTGTTCGGTAACCTTATAGCGCTCTCACTAGGCCTG ACACCAAATTTTAAGTCGAACTTCGACTTAGCTGAAGATGCCAAATTGCAGCTTAGTAAGGA 20 CACGTACGATGACGATCTCGACAATCTACTGGCACAAATTGGAGATCAGTATGCGGACTTAT TTTTGGCTGCCAAAAACCTTAGCGATGCAATCCTCCTATCTGACATACTGAGAGTTAATACT GAGATTACCAAGGCGCCGTTATCCGCTTCAATGATCAAAAGGTACGATGAACATCACCAAGA CTTGACACTTCTCAAGGCCCTAGTCCGTCAGCAACTGCCTGAGAAATATAAGGAAATATTCT TTGATCAGTCGAAAAACGGGTACGCAGGTTATATTGACGGCGGAGCGAGTCAAGAGGAATTC 25 TACAAGTTTATCAAACCCATATTAGAGAAGATGGATGGGACGGAAGAGTTGCTTGTAAAACT CAATCGCGAAGATCTACTGCGAAAGCAGCGGACTTTCGACAACGGTAGCATTCCACATCAAA TCCACTTAGGCGAATTGCATGCTATACTTAGAAGGCAGGAGGATTTTTATCCGTTCCTCAAA GACAATCGTGAAAAGATTGAGAAAATCCTAACCTTTCGCATACCTTACTATGTGGGACCCCT GGCCCGAGGGAACTCTCGGTTCGCATGGATGACAAGAAAGTCCGAAGAAACGATTACTCCAT 30 GGAATTTTGAGGAAGTTGTCGATAAAGGTGCGTCAGCTCAATCGTTCATCGAGAGGATGACC AACTTTGACAAGAATTTACCGAACGAAAAAGTATTGCCTAAGCACAGTTTACTTTACGAGTA TTTCACAGTGTACAATGAACTCACGAAAGTTAAGTATGTCACTGAGGGCATGCGTAAACCCG CCTTTCTAAGCGGAGAACAGAAGAAAGCAATAGTAGATCTGTTATTCAAGACCAACCGCAAA GTGACAGTTAAGCAATTGAAAGAGGACTACTTTAAGAAAATTGAATGCTTCGATTCTGTCGA 2020221355   24 Feb 2026 GATCTCCGGGGTAGAAGATCGATTTAATGCGTCACTTGGTACGTATCATGACCTCCTAAAGA TAATTAAAGATAAGGACTTCCTGGATAACGAAGAGAATGAAGATATCTTAGAAGATATAGTG TTGACTCTTACCCTCTTTGAAGATCGGGAAATGATTGAGGAAAGACTAAAAACATACGCTCA CCTGTTCGACGATAAGGTTATGAAACAGTTAAAGAGGCGTCGCTATACGGGCTGGGGACGAT 5 TGTCGCGGAAACTTATCAACGGGATAAGAGACAAGCAAAGTGGTAAAACTATTCTCGATTTT CTAAAGAGCGACGGCTTCGCCAATAGGAACTTTATGCAGCTGATCCATGATGACTCTTTAAC CTTCAAAGAGGATATACAAAAGGCACAGGTTTCCGGACAAGGGGACTCATTGCACGAACATA TTGCGAATCTTGCTGGTTCGCCAGCCATCAAAAAGGGCATACTCCAGACAGTCAAAGTAGTG GATGAGCTAGTTAAGGTCATGGGACGTCACAAACCGGAAAACATTGTAATCGAGATGGCACG 10 CGAAAATCAAACGACTCAGAAGGGGCAAAAAAACAGTCGAGAGCGGATGAAGAGAATAGAAG AGGGTATTAAAGAACTGGGCAGCCAGATCTTAAAGGAGCATCCTGTGGAAAATACCCAATTG CAGAACGAGAAACTTTACCTCTATTACCTACAAAATGGAAGGGACATGTATGTTGATCAGGA ACTGGACATAAACCGTTTATCTGATTACGACGTCGATCACATTGTACCCCAATCCTTTTTGA AGGACGATTCAATCGACAATAAAGTGCTTACACGCTCGGATAAGAACCGAGGGAAAAGTGAC 15 AATGTTCCAAGCGAGGAAGTCGTAAAGAAAATGAAGAACTATTGGCGGCAGCTCCTAAATGC GAAACTGATAACGCAAAGAAAGTTCGATAACTTAACTAAAGCTGAGAGGGGTGGCTTGTCTG AACTTGACAAGGCCGGATTTATTAAACGTCAGCTCGTGGAAACCCGCCAAATCACAAAGCAT GTTGCACAGATACTAGATTCCCGAATGAATACGAAATACGACGAGAACGATAAGCTGATTCG GGAAGTCAAAGTAATCACTTTAAAGTCAAAATTGGTGTCGGACTTCAGAAAGGATTTTCAAT 20 TCTATAAAGTTAGGGAGATAAATAACTACCACCATGCGCACGACGCTTATCTTAATGCCGTC GTAGGGACCGCACTCATTAAGAAATACCCGAAGCTAGAAAGTGAGTTTGTGTATGGTGATTA CAAAGTTTATGACGTCCGTAAGATGATCGCGAAAAGCGAACAGGAGATAGGCAAGGCTACAG CCAAATACTTCTTTTATTCTAACATTATGAATTTCTTTAAGACGGAAATCACTCTGGCAAAC GGAGAGATACGCAAACGACCTTTAATTGAAACCAATGGGGAGACAGGTGAAATCGTATGGGA 25 TAAGGGCCGGGACTTCGCGACGGTGAGAAAAGTTTTGTCCATGCCCCAAGTCAACATAGTAA AGAAAACTGAGGTGCAGACCGGAGGGTTTTCAAAGGAATCGATTCTTCCAAAAAGGAATAGT GATAAGCTCATCGCTCGTAAAAAGGACTGGGACCCGAAAAAGTACGGTGGCTTCGATAGCCC TACAGTTGCCTATTCTGTCCTAGTAGTGGCAAAAGTTGAGAAGGGAAAATCCAAGAAACTGA AGTCAGTCAAAGAATTATTGGGGATAACGATTATGGAGCGCTCGTCTTTTGAAAAGAACCCC 30 ATCGACTTCCTTGAGGCGAAAGGTTACAAGGAAGTAAAAAAGGATCTCATAATTAAACTACC AAAGTATAGTCTGTTTGAGTTAGAAAATGGCCGAAAACGGATGTTGGCTAGCGCCGGAGAGC TTCAAAAGGGGAACGAACTCGCACTACCGTCTAAATACGTGAATTTCCTGTATTTAGCGTCC CATTACGAGAAGTTGAAAGGTTCACCTGAAGATAACGAACAGAAGCAACTTTTTGTTGAGCA GCACAAACATTATCTCGACGAAATCATAGAGCAAATTTCGGAATTCAGTAAGAGAGTCATCC 2020221355   24 Feb 2026 TAGCTGATGCCAATCTGGACAAAGTATTAAGCGCATACAACAAGCACAGGGATAAACCCATA CGTGAGCAGGCGGAAAATATTATCCATTTGTTTACTCTTACCAACCTCGGCGCTCCAGCCGC ATTCAAGTATTTTGACACAACGATAGATCGCAAACGATACACTTCTACCAAGGAGGTGCTAG ACGCGACACTGATTCACCAATCCATCACGGGATTATATGAAACTCGGATAGATTTGTCACAG 5 CTTGGGGGTGACGGATCCCCCAAGAAGAAGAGGAAAGTCTCGAGCGACTACAAAGACCATGA CGGTGATTATAAAGATCATGACATCGATTACAAGGATGACGATGACAAGGCTGCAGGA MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD 10 EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK 15 DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV 20 DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGF1KRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN 25 GEIRKRPLXETNGETGEIVWDKGRDFATVRKVLSMPQVNXVKKTEVQTGGFSKE SIL PKRN S DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ 30 LGGD (single underline: HNH domain; double underline: RuvC domain). In some embodiments, wild-type Cas9 corresponds to Cas9 from Streptococcus pyogenes (NCBI Reference Sequence: NC_002737.2 (nucleotide sequence as follows); and Uniprot Reference Sequence: Q99ZW2 (amino acid sequence as follows): 2020221355   24 Feb 2026 ATGGATAAGAAATACTCAATAGGCTTAGATATCGGCACAAATAGCGTCGGATGGGCGGTGAT CACTGATGAATATAAGGTTCCGTCTAAAAAGTTCAAGGTTCTGGGAAATACAGACCGCCACA GTATCAAAAAAAATCTTATAGGGGCTCTTTTATTTGACAGTGGAGAGACAGCGGAAGCGACT CGTCTCAAACGGACAGCTCGTAGAAGGTATACACGTCGGAAGAATCGTATTTGTTATCTACA 5 GGAGATTTTTTCAAATGAGATGGCGAAAGTAGATGATAGTTTCTTTCATCGACTTGAAGAGT CTTTTTTGGTGGAAGAAGACAAGAAGCATGAACGTCATCCTATTTTTGGAAATATAGTAGAT GAAGTTGCTTATCATGAGAAATATCCAACTATCTATCATCTGCGAAAAAAATTGGTAGATTC TACTGATAAAGCGGATTTGCGCTTAATCTATTTGGCCTTAGCGCATATGATTAAGTTTCGTG GTCATTTTTTGATTGAGGGAGATTTAAATCCTGATAATAGTGATGTGGACAAACTATTTATC 10 CAGTTGGTACAAACCTACAATCAATTATTTGAAGAAAACCCTATTAACGCAAGTGGAGTAGA TGCTAAAGCGATTCTTTCTGCACGATTGAGTAAATCAAGACGATTAGAAAATCTCATTGCTC AGCTCCCCGGTGAGAAGAAAAATGGCTTATTTGGGAATCTCATTGCTTTGTCATTGGGTTTG ACCCCTAATTTTAAATCAAATTTTGATTTGGCAGAAGATGCTAAATTACAGCTTTCAAAAGA TACTTACGATGATGATTTAGATAATTTATTGGCGCAAATTGGAGATCAATATGCTGATTTGT 15 TTTTGGCAGCTAAGAATTTATCAGATGCTATTTTACTTTCAGATATCCTAAGAGTAAATACT GAAATAACTAAGGCTCCCCTATCAGCTTCAATGATTAAACGCTACGATGAACATCATCAAGA CTTGACTCTTTTAAAAGCTTTAGTTCGACAACAACTTCCAGAAAAGTATAAAGAAATCTTTT TTGATCAATCAAAAAACGGATATGCAGGTTATATTGATGGGGGAGCTAGCCAAGAAGAATTT TATAAATTTATCAAACCAATTTTAGAAAAAATGGATGGTACTGAGGAATTATTGGTGAAACT 20 AAATCGTGAAGATTTGCTGCGCAAGCAACGGACCTTTGACAACGGCTCTATTCCCCATCAAA TTCACTTGGGTGAGCTGCATGCTATTTTGAGAAGACAAGAAGACTTTTATCCATTTTTAAAA GACAATCGTGAGAAGATTGAAAAAATCTTGACTTTTCGAATTCCTTATTATGTTGGTCCATT GGCGCGTGGCAATAGTCGTTTTGCATGGATGACTCGGAAGTCTGAAGAAACAATTACCCCAT GGAATTTTGAAGAAGTTGTCGATAAAGGTGCTTCAGCTCAATCATTTATTGAACGCATGACA 25 AACTTTGATAAAAATCTTCCAAATGAAAAAGTACTACCAAAACATAGTTTGCTTTATGAGTA TTTTACGGTTTATAACGAATTGACAAAGGTCAAATATGTTACTGAAGGAATGCGAAAACCAG CATTTCTTTCAGGTGAACAGAAGAAAGCCATTGTTGATTTACTCTTCAAAACAAATCGAAAA GTAACCGTTAAGCAATTAAAAGAAGATTATTTCAAAAAAATAGAATGTTTTGATAGTGTTGA AATTTCAGGAGTTGAAGATAGATTTAATGCTTCATTAGGTACCTACCATGATTTGCTAAAAA 30 TTATTAAAGATAAAGATTTTTTGGATAATGAAGAAAATGAAGATATCTTAGAGGATATTGTT TTAACATTGACCTTATTTGAAGATAGGGAGATGATTGAGGAAAGACTTAAAACATATGCTCA CCTCTTTGATGATAAGGTGATGAAACAGCTTAAACGTCGCCGTTATACTGGTTGGGGACGTT TGTCTCGAAAATTGATTAATGGTATTAGGGATAAGCAATCTGGCAAAACAATATTAGATTTT TTGAAATCAGATGGTTTTGCCAATCGCAATTTTATGCAGCTGATCCATGATGATAGTTTGAC 2020221355   24 Feb 2026 ATTTAAAGAAGACATTCAAAAAGCACAAGTGTCTGGACAAGGCGATAGTTTACATGAACATA TTGCAAATTTAGCTGGTAGCCCTGCTATTAAAAAAGGTATTTTACAGACTGTAAAAGTTGTT GATGAATTGGTCAAAGTAATGGGGCGGCATAAGCCAGAAAATATCGTTATTGAAATGGCACG TGAAAATCAGACAACTCAAAAGGGCCAGAAAAATTCGCGAGAGCGTATGAAACGAATCGAAG 5 AAGGTATCAAAGAATTAGGAAGTCAGATTCTTAAAGAGCATCCTGTTGAAAATACTCAATTG CAAAATGAAAAGCTCTATCTCTATTATCTCCAAAATGGAAGAGACATGTATGTGGACCAAGA ATTAGATATTAATCGTTTAAGTGATTATGATGTCGATCACATTGTTCCACAAAGTTTCCTTA AAGACGATTCAATAGACAATAAGGTCTTAACGCGTTCTGATAAAAATCGTGGTAAATCGGAT AACGTTCCAAGTGAAGAAGTAGTCAAAAAGATGAAAAACTATTGGAGACAACTTCTAAACGC 10 CAAGTTAATCACTCAACGTAAGTTTGATAATTTAACGAAAGCTGAACGTGGAGGTTTGAGTG AACTTGATAAAGCTGGTTTTATCAAACGCCAATTGGTTGAAACTCGCCAAATCACTAAGCAT GTGGCACAAATTTTGGATAGTCGCATGAATACTAAATACGATGAAAATGATAAACTTATTCG AGAGGTTAAAGTGATTACCTTAAAATCTAAATTAGTTTCTGACTTCCGAAAAGATTTCCAAT TCTATAAAGTACGTGAGATTAACAATTACCATCATGCCCATGATGCGTATCTAAATGCCGTC 15 GTTGGAACTGCTTTGATTAAGAAATATCCAAAACTTGAATCGGAGTTTGTCTATGGTGATTA TAAAGTTTATGATGTTCGTAAAATGATTGCTAAGTCTGAGCAAGAAATAGGCAAAGCAACCG CAAAATATTTCTTTTACTCTAATATCATGAACTTCTTCAAAACAGAAATTACACTTGCAAAT GGAGAGATTCGCAAACGCCCTCTAATCGAAACTAATGGGGAAACTGGAGAAATTGTCTGGGA TAAAGGGCGAGATTTTGCCACAGTGCGCAAAGTATTGTCCATGCCCCAAGTCAATATTGTCA 20 AGAAAACAGAAGTACAGACAGGCGGATTCTCCAAGGAGTCAATTTTACCAAAAAGAAATTCG GACAAGCTTATTGCTCGTAAAAAAGACTGGGATCCAAAAAAATATGGTGGTTTTGATAGTCC AACGGTAGCTTATTCAGTCCTAGTGGTTGCTAAGGTGGAAAAAGGGAAATCGAAGAAGTTAA AATCCGTTAAAGAGTTACTAGGGATCACAATTATGGAAAGAAGTTCCTTTGAAAAAAATCCG ATTGACTTTTTAGAAGCTAAAGGATATAAGGAAGTTAAAAAAGACTTAATCATTAAACTACC 25 TAAATATAGTCTTTTTGAGTTAGAAAACGGTCGTAAACGGATGCTGGCTAGTGCCGGAGAAT TACAAAAAGGAAATGAGCTGGCTCTGCCAAGCAAATATGTGAATTTTTTATATTTAGCTAGT CATTATGAAAAGTTGAAGGGTAGTCCAGAAGATAACGAACAAAAACAATTGTTTGTGGAGCA GCATAAGCATTATTTAGATGAGATTATTGAGCAAATCAGTGAATTTTCTAAGCGTGTTATTT TAGCAGATGCCAATTTAGATAAAGTTCTTAGTGCATATAACAAACATAGAGACAAACCAATA 30 CGTGAACAAGCAGAAAATATTATTCATTTATTTACGTTGACGAATCTTGGAGCTCCCGCTGC TTTTAAATATTTTGATACAACAATTGATCGTAAACGATATACGTCTACAAAAGAAGTTTTAG ATGCCACTCTTATCCATCAATCCATCACTGGTCTTTATGAAACACGCATTGATTTGAGTCAG CTAGGAGGTGACTGA 2020221355   24 Feb 2026 MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL 5 TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK 10 VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD 15 NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP 20 IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD (single underline: HNH domain; double underline: RuvC domain) In some embodiments, Cas9 refers to Cas9 from: Corynebacterium ulcerans (NCBI 25 Refs: NC_015683.1, NC_017317.1); Corynebacterium diphtheria (NCBI Refs: NC_016782.1, NC_016786.1); Spiroplasma syrphidicola (NCBI Ref: NC_021284.1); Prevotella intermedia (NCBI Ref: NC_017861.1); Spiroplasma taiwanense (NCBI Ref: NC_021846.1); Streptococcus iniae (NCBI Ref: NC_021314.1); Belliella baltica (NCBI Ref: NC_018010.1); Psychroflexus torquisI (NCBI Ref: NC_018721.1); Streptococcus 30 thermophilus (NCBI Ref: YP_820832.1), Listeria innocua (NCBI Ref: NP_472073.1), Campylobacter jejuni (NCBI Ref: YP_002344900.1) or Neisseria meningitidis (NCBI Ref: YP_002342100.1) or to a Cas9 from any other organism. It should be appreciated that additional Cas9 proteins (e.g., a nuclease dead Cas9 (dCas9), a Cas9 nickase (nCas9), or a nuclease active Cas9), including variants and homologs 2020221355   24 Feb 2026 thereof, are within the scope of this disclosure. Exemplary Cas9 proteins include, without limitation, those provided below. In some embodiments, the Cas9 protein is a nuclease dead Cas9 (dCas9). In some embodiments, the Cas9 protein is a Cas9 nickase (nCas9). In some embodiments, the Cas9 protein is a nuclease active Cas9. 5          In some embodiments, the Cas9 domain is a nuclease-inactive Cas9 domain (dCas9). For example, the dCas9 domain may bind to a duplexed nucleic acid molecule (e.g., via a gRNA molecule) without cleaving either strand of the duplexed nucleic acid molecule. In some embodiments, the nuclease-inactive dCas9 domain comprises a D10X mutation and a H840X mutation of the amino acid sequence set forth herein, or a corresponding mutation in 10 any of the amino acid sequences provided herein, wherein X is any amino acid change. In some embodiments, the nuclease-inactive dCas9 domain comprises a D10A mutation and a H840A mutation of the amino acid sequence set forth herein, or a corresponding mutation in any of the amino acid sequences provided herein. As one example, a nuclease-inactive Cas9 domain comprises the amino acid sequence set forth in Cloning vector pPlatTET-gRNA2 15 (Accession No. BAV54124). The amino acid sequence of an exemplary catalytically inactive Cas9 (dCas9) is as follows: MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD 20 EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK 25 DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV 30 DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDAIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN 2020221355   24 Feb 2026 GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI 5 REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD (see, e.g., Qi et al., “Repurposing CRISPR as an RNA-guided platform for sequencespecific control of gene expression.” Cell. 2013; 152(5):1173-83, the entire contents of which are incorporated herein by reference). Additional suitable nuclease-inactive dCas9 domains will be apparent to those of skill 10 in the art based on this disclosure and knowledge in the field, and are within the scope of this disclosure. Such additional exemplary suitable nuclease-inactive Cas9 domains include, but are not limited to, D10A / H840A, D10A / D839A / H840A, and D10A / D839A / H840A / N863A mutant domains (See, e.g., Prashant et al., CAS9 transcriptional activators for target specificity screening and paired nickases for cooperative genome engineering. Nature 15   Biotechnology. 2013; 31(9): 833-838, the entire contents of which are incorporated herein by reference). In some embodiments, a Cas9 nuclease has an inactive (e.g., an inactivated) DNA cleavage domain, that is, the Cas9 is a nickase, referred to as an “nCas9” protein (for “nickase” Cas9). A nuclease-inactivated Cas9 protein may interchangeably be referred to as 20 a “dCas9” protein (for nuclease-“dead” Cas9) or catalytically inactive Cas9. Methods for generating a Cas9 protein (or a fragment thereof) having an inactive DNA cleavage domain are known (See, e.g., Jinek et al., Science. 337:816-821(2012); Qi et al., “Repurposing CRISPR as an RNA-Guided Platform for Sequence-Specific Control of Gene Expression” (2013) Cell. 28;152(5):1173-83, the entire contents of each of which are incorporated herein 25 by reference). For example, the DNA cleavage domain of Cas9 is known to include two subdomains, the HNH nuclease subdomain and the RuvC1 subdomain. The HNH subdomain cleaves the strand complementary to the gRNA, whereas the RuvC1 subdomain cleaves the non-complementary strand. Mutations within these subdomains can silence the nuclease activity of Cas9. For example, the mutations D10A and H840A completely inactivate the 30 nuclease activity of S. pyogenes Cas9 (Jinek et al., Science. 337:816-821(2012); Qi et al., Cell. 28;152(5):1173-83 (2013)). In some embodiments, the dCas9 domain comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at 2020221355   24 Feb 2026 least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the dCas9 domains provided herein. In some embodiments, the Cas9 domain comprises an amino acid sequences that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 21, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 5   42, 43, 44, 45, 46, 47, 48, 49, 50 or more or more mutations compared to any one of the amino acid sequences set forth herein. In some embodiments, the Cas9 domain comprises an amino acid sequence that has at least 10, at least 15, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 500, at least 600, at least 700, at least 10   800, at least 900, at least 1000, at least 1100, or at least 1200 identical contiguous amino acid residues as compared to any one of the amino acid sequences set forth herein. In some embodiments, dCas9 corresponds to, or comprises in part or in whole, a Cas9 amino acid sequence having one or more mutations that inactivate the Cas9 nuclease activity. For example, in some embodiments, a dCas9 domain comprises D10A and an H840A 15 mutation or corresponding mutations in another Cas9. In some embodiments, the dCas9 comprises the amino acid sequence of dCas9 (D10A and H840A): MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD 20 EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK 25 DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKE DIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV 30 DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDAIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGF1KRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN 2020221355   24 Feb 2026 GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESIL PKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI 5 REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD (single underline: HNH domain; double underline: RuvC domain). In some embodiments, the Cas9 domain comprises a D10A mutation, while the residue at position 840 remains a histidine in the amino acid sequence provided above, or at corresponding positions in any of the amino acid sequences provided herein. 10         In other embodiments, dCas9 variants having mutations other than D10A and H840A are provided, which, e.g., result in nuclease inactivated Cas9 (dCas9). Such mutations, by way of example, include other amino acid substitutions at D10 and H840, or other substitutions within the nuclease domains of Cas9 (e.g., substitutions in the HNH nuclease subdomain and / or the RuvC1 subdomain). In some embodiments, variants or homologues of 15 dCas9 are provided which are at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical. In some embodiments, variants of dCas9 are provided having amino acid sequences which are shorter, or longer, by about 5 amino acids, by about 10 amino acids, by about 15 amino acids, 20 by about 20 amino acids, by about 25 amino acids, by about 30 amino acids, by about 40 amino acids, by about 50 amino acids, by about 75 amino acids, by about 100 amino acids or more. In some embodiments, the Cas9 domain is a Cas9 nickase. The Cas9 nickase may be a Cas9 protein that is capable of cleaving only one strand of a duplexed nucleic acid molecule 25   (e.g., a duplexed DNA molecule). In some embodiments the Cas9 nickase cleaves the target strand of a duplexed nucleic acid molecule, meaning that the Cas9 nickase cleaves the strand that is base paired to (complementary to) a gRNA (e.g., an sgRNA) that is bound to the Cas9. In some embodiments, a Cas9 nickase comprises a D10A mutation and has a histidine at position 840. In some embodiments the Cas9 nickase cleaves the non-target, non-base-edited 30 strand of a duplexed nucleic acid molecule, meaning that the Cas9 nickase cleaves the strand that is not base paired to a gRNA (e.g., an sgRNA) that is bound to the Cas9. In some embodiments, a Cas9 nickase comprises an H840A mutation and has an aspartic acid residue at position 10, or a corresponding mutation. In some embodiments the Cas9 nickase 2020221355   24 Feb 2026 comprises an amino acid sequence that is 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 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the Cas9 nickases provided herein. Additional suitable Cas9 nickases will be apparent to those of skill in the art based on 5 this disclosure and knowledge in the field, and are within the scope of this disclosure. The amino acid sequence of an exemplary catalytically Cas9 nickase (nCas9) is as follows: MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI 10 QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT 15 NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL 20 QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS 25 DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD 30          In some embodiments, Cas9 refers to a Cas9 from archaea (e.g., nanoarchaea), which constitute a domain and kingdom of single-celled prokaryotic microbes. In some embodiments, the nucleic acid programmable DNA binding protein refers to CasX or CasY, which have been described in, for example, Burstein et al., "New CRISPR-Cas systems from uncultivated microbes." Cell Res. 2017 Feb 21. doi: 10.1038 / cr.2017.21, the entire contents 2020221355   24 Feb 2026 of which is hereby incorporated by reference. Using genome-resolved metagenomics, a number of CRISPR-Cas systems were identified, including the first reported Cas9 in the archaeal domain of life. This divergent Cas9 protein was found in little-studied nanoarchaea as part of an active CRISPR-Cas system. In bacteria, two previously unknown systems were 5 discovered, CRISPR-CasX and CRISPR-CasY, which are among the most compact systems yet discovered. In some embodiments, in a base editor system described herein Cas9 is replaced by CasX, or a variant of CasX. In some embodiments, in a base editor system described herein Cas9 is replaced by CasY, or a variant of CasY. It should be appreciated that other RNA-guided DNA binding proteins may be used as a nucleic acid programmable DNA 10 binding protein (napDNAbp), and are within the scope of this disclosure. In some embodiments, the nucleic acid programmable DNA binding protein (napDNAbp) of any of the fusion proteins provided herein may be a CasX or CasY protein. In some embodiments, the napDNAbp is a CasX protein. In some embodiments, the napDNAbp is a CasY protein. In some embodiments, the napDNAbp comprises an amino 15 acid sequence that is 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 at ease 99.5% identical to a naturally-occurring CasX or CasY protein. In some embodiments, the programmable nucleotide binding protein is a naturally-occurring CasX or CasY protein. In some embodiments, the programmable nucleotide binding protein comprises an amino acid 20 sequence that is 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 at ease 99.5% identical to any CasX or CasY protein described herein. It should be appreciated that CasX and CasY from other bacterial species may also be used in accordance with the present disclosure. 25          An exemplary CasX ((uniprot.org / uniprot / F0NN87; uniprot.org / uniprot / F0NH53) tr|F0NN87|F0NN87_SULIHCRISPR-associatedCasx protein OS = Sulfolobus islandicus (strain HVE10 / 4) GN = SiH_0402 PE=4 SV=1) amino acid sequence is as follows: MEVPLYNIFGDNYIIQVATEAENSTIYNNKVEIDDEELRNVLNLAYKIAKNNEDAAAERRGK AKKKKGEEGETTTSNIILPLSGNDKNPWTETLKCYNFPTTVALSEVFKNFSQVKECEEVSAP 30 SFVKPEFYEFGRSPGMVERTRRVKLEVEPHYLIIAAAGWVLTRLGKAKVSEGDYVGVNVFTP TRGILYSLIQNVNGIVPGIKPETAFGLWIARKVVSSVTNPNVSVVRIYTISDAVGQNPTTIN GGFSIDLTKLLEKRYLLSERLEAIARNALSISSNMRERYIVLANYIYEYLTG SKRLEDLLY FANRDLIMNLNSDDGKVRDLKLISAYVNGELIRGEG. 2020221355   24 Feb 2026 An exemplary CasX (>tr|F0NH53|F0NH53_SULIR CRISPR associated protein, Casx OS = Sulfolobus islandicus (strain REY15A) GN=SiRe_0771 PE=4 SV=1) amino acid sequence is as follows: MEVPLYNIFGDNYIIQVATEAENSTIYNNKVEIDDEELRNVLNLAYKIAKNNEDAAAERRGK 5 AKKKKGEEGETTTSNIILPLSGNDKNPWTETLKCYNFPTTVALSEVFKNFSQVKECEEVSAP SFVKPEFYKFGRSPGMVERTRRVKLEVEPHYLIMAAAGWVLTRLGKAKVSEGDYVGVNVFTP TRGILYSLIQNVNGIVPGIKPETAFGLWIARKVVSSVTNPNVSVVSIYTISDAVGQNPTTIN GGFSIDLTKLLEKRDLLSERLEAIARNALSISSNMRERYIVLANYIYEYLTGSKRLEDLLYF ANRDLIMNLNSDDGKVRDLKLISAYVNGELIRGEG. 10 Deltaproteobacteria CasX MEKRINKIRKKLSADNATKPVSRSGPMKTLLVRVMTDDLKKRLEKRRKKPEVMPQVISNNAA NNLRMLLDDYTKMKEAILQVYWQEFKDDHVGLMCKFAQPASKKIDQNKLKPEMDEKGNLTTA GFACSQCGQPLFVYKLEQVSEKGKAYTNYFGRCNVAEHEKLILLAQLKPVKDSDEAVTYSLG 15 KFGQRALDFYSIHVTKESTHPVKPLAQIAGNRYASGPVGKALSDACMGTIASFLSKYQDIII EHQKVVKGNQKRLESLRELAGKENLEYPSVTLPPQPHTKEGVDfAYNEVIARVRMWVNLNLW QKLKLSRDDAKPLLRLKGFPSFPVVERRENEVDWWNTINEVKKLIDAKRDMGRVFWSGVTAE KRNTILEGYNYLPNENDHKKREGSLENPKKPAKRQFGDLLLYLEKKYAGDWGKVFDEAWERI DKKIAGLTSHIEREEARNAEDAQSKAVLTDWLRAKASFVLERLKEMDEKEFYACEIQLQKWY 20 GDLRGNPFAVEAENRVVDISGFSIGSDGHSIQYRNLLAWKYLENGKREFYLLMNYGKKGRIR FTDGTDIKKSGKWQGLLYGGGKAKVIDLTFDPDDEQLIILPLAFGTRQGREFIWNDLLSLET GLIKLANGRVIEKTIYNKKIGRDEPALFVALTFERREVVDPSNIKPVNLIGVARGENIPAVI ALTDPEGCPLPEFKDSSGGPTDILRIGEGYKEKQRAIQAAKEVEQRRAGGYSRKFASKSRNL ADDMVRNSARDLFYHAVTHDAVLVFANLSRGFGRQGKRTFMTERQYTKMEDWLTAKLAYEGL 25 TSKTYLSKTLAQYTSKTCSNCGFTITYADMDVMLVRLKKTSDGWATTLNNKELKAEYQITYY NRYKRQTVEKELSAELDRLSEESGNNDISKWTKGRRDEALFLLKKRFSHRPVQEQFVCLDCG HEVHAAEQAALNIARSWLFLNSNSTEFKSYKSGKQPFVGAWQAFYKRRLKEVWKPNA An exemplary CasY ((ncbi.nlm.nih.gov / protein / APG80656.1) >APG80656.1 CRISPR-associated protein CasY [uncultured Parcubacteria group bacterium]) amino acid 30 sequence is as follows: MSKRHPRISGVKGYRLHAQRLEYTGKSGAMRTIKYPLYSSPSGGRTVPREIVSAINDDYVGL YGLSNFDDLYNAEKRNEEKVYSVLDFWYDCVQYGAVFSYTAPGLLKNVAEVRGGSYELTKTL KGSHLYDELQIDKVIKFLNKKEISRANGSLDKLKKDIIDCFKAEYRERHKDQCNKLADDIKN AKKDAGASLGERQKKLFRDFFGISEQSENDKPSFTNPLNLTCCLLPFDTVNNNRNRGEVLFN 2020221355   24 Feb 2026 KLKEYAQKLDKNEGSLEMWEYIGIGNSGTAFSNFLGEGFLGRLRENKITELKKAMMDITDAW RGQEQEEELEKRLRILAALTIKLREPKFDNHWGGYRSDINGKLSSWLQNYINQTVKIKEDLK GHKKDLKKAKEMINRFGESDTKEEAVVSSLLESIEKIVPDDSADDEKPDIPAIAIYRRFLSD GRLTLNRFVQREDVQEALIKERLEAEKKKKPKKRKKKSDAEDEKETIDFKELFPHLAKPLKL 5 VPNFYGDSKRELYKKYKNAAIYTDALWKAVEKIYKSAFSSSLKNSFFDTDFDKDFFIKRLQK IFSVYRRFNTDKWKPIVKNSFAPYCDIVSLAENEVLYKPKQSRSRKSAAIDKNRVRLPSTEN IAKAGIALARELSVAGFDWKDLLKKEEHEEYIDLIELHKTALALLLAVTETQLDISALDFVE NGTVKDFMKTRDGNLVLEGRFLEMFSQSIVFSELRGLAGLMSRKEFITRSAIQTMNGKQAEL LYIPHEFQSAKITTPKEMSRAFLDLAPAEFATSLEPESLSEKSLLKLKQMRYYPHYFGYELT 10 RTGQGIDGGVAENALRLEKSPVKKREIKCKQYKTLGRGQNKIVLYVRSSYYQTQFLEWFLHR PKNVQTDVAVSGSFLIDEKKVKTRWNYDALTVALEPVSGSERVFVSQPFTIFPEKSAEEEGQ RYLGIDIGEYGIAYTALEITGDSAKILDQNFISDPQLKTLREEVKGLKLDQRRGTFAMPSTK IARIRESLVHSLRNRIHHLALKHKAKIVYELEVSRFEEGKQKIKKVYATLKKADVYSEIDAD KNLQTTVWGKLAVASEISASYTSQFCGACKKLWRAEMQVDETITTQELIGTVRVIKGGTLID 15 AIKDFMRPPIFDENDTPFPKYRDFCDKHHISKKMRGNSCLFICPFCRANADADIQASQTIAL LRYVKEEKKVEDYFERFRKLKNIKVLGQMKKI. The Cas9 nuclease has two functional endonuclease domains: RuvC and HNH. Cas9 undergoes a conformational change upon target binding that positions the nuclease domains to cleave opposite strands of the target DNA. The end result of Cas9-mediated DNA 20 cleavage is a double-strand break (DSB) within the target DNA (~3-4 nucleotides upstream of the PAM sequence). The resulting DSB is then repaired by one of two general repair pathways: (1) the efficient but error-prone non-homologous end joining (NHEJ) pathway; or (2) the less efficient but high-fidelity homology directed repair (HDR) pathway. The “efficiency” of non-homologous end joining (NHEJ) and / or homology directed 25 repair (HDR) can be calculated by any convenient method. For example, in some embodiments, efficiency can be expressed in terms of percentage of successful HDR. For example, a surveyor nuclease assay can be used to generate cleavage products and the ratio of products to substra...

Claims

1. A method of editing a glucose-6-phosphatase (G6PC) polynucleotide comprising a single nucleotide polymorphism (SNP) associated with Glycogen Storage Disease Type 1a (GSD1a), the method comprising contacting the G6PC polynucleotide with an Adenosine Deaminase Base Editor 8 (ABE8) in a complex with one or more guide polynucleotides, wherein the ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and wherein one or more of said guide polynucleotides target said base editor to effect an A»T to OC alteration of the SNP associated with GSD1a.

2. The method of any one of claim 1, comprising one or more of:(a) the SNP associated with GSD1a changes a glutamine (Q) to a non-glutamine amino acid or changes an arginine (R) to a non-arginine amino acid in the G6PC polypeptide;(b) the SNP associated with GSD1a results in expression of an G6PC polypeptide having a nonglutamine amino acid at position 347 or a non-arginine amino acid at position 83;(c) the base editor correction replaces the non-glutamine amino acid at position 347 with a glutamine or the non-arginine amino acid at position 83 with an arginine;(d) the SNP associated with GSD1a results in expression of a G6PC polypeptide that prematurely terminates at amino acid position 347 or that comprises a cysteine at position 83;(e) the SNP encodes one or more of Q347X or R83C;(f) the polynucleotide programmable DNA binding domain is a Streptococcus pyogenes Cas9 (SpCas9) or a variant thereof;2020221355   24 Apr 2026(g) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having an altered protospacer-adjacent motif (PAM) specificity or specificity for a non-G PAM;(h) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 and the modified SpCas9 has specificity for the nucleic acid sequence 5’-NGA-3’;(i) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 and the modified SpCas9 has specificity for the nucleic acid sequence 5’-AGA-3’ or 5’-GGA-3’;(j) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 and the modified SpCas9 has specificity for an NGA PAM variant;(k) the polynucleotide programmable DNA binding domain is a Staphylococcus aureus Cas9 (SaCas9) or variant thereof;(l) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having protospacer-adjacent motif (PAM) specificity for the nucleic acid sequence 5’-NNGRRT-3’;(m) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for the nucleic acid sequence 5’-GAGAAT-3’;(n) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for an NNGRRT PAM variant;(o) the polynucleotide programmable DNA binding domain is a nuclease inactive variant;(p) the polynucleotide programmable DNA binding domain is a nickase variant;(q) the polynucleotide programmable DNA binding domain is a nickase variant and the nickase variant comprises an amino acid substitution D10A or a corresponding amino acid substitution; (r) the adenosine deaminase domain is a monomer comprising an adenosine deaminase variant; (s) the adenosine deaminase domain further comprises a wild-type adenosine deaminase domain; (t) the adenosine deaminase variant further comprises an alteration selected from the group consisting of Y123H and Q154R;(u) the adenosine deaminase variant comprises a combination of alterations selected from the group consisting of:Y147T and Q154R;Y147T and Q154S;Y147R and Q154S;V82S and Q154S;V82S and Y147R;2020221355   24 Apr 2026V82S and Q154R;V82S and Y123H;I76Y and V82S;V82S, Y123H, and Y147T;V82S, Y123H, and Y147R;V82S, Y123H, and Q154R;Y147R, Q154R, and Y123H;Y147R, Q154R, and I76Y;Y147R, Q154R, and T166R;Y123H, Y147R, Q154R, and I76Y;V82S, Y123H, Y147R, and Q154R; and I76Y, V82S, Y123H, Y147R, and Q154R;(v) the adenosine deaminase variant comprises the alterations Y147T, and Q154S;(w) the guide polynucleotide comprises a nucleic acid sequence selected from the group consisting of:a) GACCUAGGCGAGGCAGUAGG;b) CCAGUAUGGACACUGUCCAAA;c) CAGUAUGGACACUGUCCAAA; andd) AGUAUGGACACUGUCCAAAG;(x) the adenosine deaminase variant is a TadA deaminase;(y) the adenosine deaminase variant is a TadA deaminase and the TadA deaminase is selected from the group consisting of: TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.5, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, and TadA*8.24;(z) the ABE8 is selected from the group consisting of: ABE8.1-m, ABE8.2-m, ABE8.3-m, ABE8.5-m, ABE8.8-m, ABE8.9-m, ABE8.10-m, ABE8.11-m, ABE8.12-m, ABE8.13-m, ABE8.14-m, ABE8.15-m, ABE8.16-m, ABE8.17-m, ABE8.18-m, ABE8.19-m, ABE8.20-m, ABE8.21-m, ABE8.22-m, ABE8.23-m, ABE8.24-m, ABE8.1-d, ABE8.2-d, ABE8.3-d, ABE8.5-d, ABE8.8-d, ABE8.9-d, ABE8.10-d, ABE8.11-d, ABE8.12-d, ABE8.13-d, ABE8.14-d,2020221355   24 Apr 2026ABE8.15-d, ABE8.16-d, ABE8.17-d, ABE8.18-d, ABE8.19-d, ABE8.20-d, ABE8.21-d, ABE8.22-d, ABE8.23-d, and ABE8.24-d;(aa) the one or more guide RNAs comprises a CRISPR RNA (crRNA) and a trans-encoded small RNA (tracrRNA), wherein the crRNA comprises a nucleic acid sequence complementary to a G6PC nucleic acid sequence comprising the SNP associated with GSD1a;(bb) the ABE8 is in complex with a single guide RNA (sgRNA) comprising a nucleic acid sequence complementary to an G6PC nucleic acid sequence comprising the SNP associated with GSD1a;(cc) the contacting is in a cell;(dd) the contacting is in a cell and the cell is a eukaryotic cell;(ee) the contacting is in a cell and the cell is a non-human mammalian cell or a human cell;(ff) the contacting is in vivo; and (gg) the contacting is ex vivo.

3. A cell comprising:an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, wherein said Adenosine Deaminase Base Editor 8 (ABE8) comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; andone or more guide polynucleotides that target the base editor to effect an A»T to OC alteration of the SNP associated with GSD1a, with the proviso that the cell is not a human ovum, a human zygote cell, a human embryo cell, or a human totipotent cell.

4. The cell of claim 3, comprising one or more of:2020221355   24 Apr 2026(a) the SNP associated with GSD1a changes a glutamine to a non-glutamine amino acid or changes an arginine to a non-arginine amino acid in the G6PC polypeptide;(b) the SNP associated with GSD1a results in expression of an G6PC polypeptide comprising a non-glutamine amino acid at position 347 or a non-arginine amino acid at position 83;(c) the base editor correction replaces the non-glutamine amino acid at position 347 with a glutamine or the non-arginine amino acid at position 83 with an arginine;(d) the SNP associated with GSD1a results in expression of a G6PC polypeptide that prematurely terminates at amino acid position 347 or that comprises a cysteine at position 83;(e) the SNP encodes one or more of Q347X and R83C;(f) the polynucleotide programmable DNA binding domain is a Streptococcus pyogenes Cas9 (SpCas9) or variant thereof;(g) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having an altered protospacer-adjacent motif (PAM) specificity or specificity for a non-G PAM;(h) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having specificity for the nucleic acid sequence 5’-NGA-3’;(i) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having specificity for the nucleic acid sequence 5’-AGA-3’ or 5’-GGA-3’;(j) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having specificity for an NGA PAM variant;(k) the polynucleotide programmable DNA binding domain is a Staphylococcus aureus Cas9 (SaCas9) or variant thereof;(l) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for the nucleic acid sequence 5’-NNGRRT-3’;(m) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for the nucleic acid sequence 5’-GAGAAT-3’;(n) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for an NNGRRT PAM variant;(o) the polynucleotide programmable DNA binding domain is a nuclease inactive variant;(p) the polynucleotide programmable DNA binding domain is a nickase variant;2020221355   24 Apr 2026(q) the polynucleotide programmable DNA binding domain is a nickase variant and the nickase variant comprises an amino acid substitution D10A or a corresponding amino acid substitution thereof;(r) the adenosine deaminase variant further comprises an alteration selected from the group consisting of: Y123H and Q154R;(s) the adenosine deaminase variant comprises a combination of alterations selected from the group consisting of:Y147T and Q154R;Y147T and Q154S;Y147R and Q154S;V82S and Q154S;V82S and Y147R;V82S and Q154R;V82S and Y123H;I76Y and V82S;V82S, Y123H, and Y147T;V82S, Y123H, and Y147R;V82S, Y123H, and Q154R;Y147R, Q154R, and Y123H;Y147R, Q154R, and I76Y;Y147R, Q154R, and T166R;Y123H, Y147R, Q154R, and I76Y;V82S, Y123H, Y147R, and Q154R; andI76Y, V82S, Y123H, Y147R, and Q154R;(t) the adenosine deaminase variant comprises the alterations Y147T and Q154S;(u) the guide polynucleotide comprises a nucleic acid sequence selected from the group consisting of:a) GACCUAGGCGAGGCAGUAGG;b) CCAGUAUGGACACUGUCCAAA;c) CAGUAUGGACACUGUCCAAA; andd) AGUAUGGACACUGUCCAAAG;2020221355   24 Apr 2026(v) the adenosine deaminase variant is a TadA deaminase;(w) the adenosine deaminase variant is a TadA deaminase and the TadA deaminase is selected from the group consisting of: TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.5, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, and TadA*8.24;(x) the adenosine deaminase domain is a monomer;(y) the adenosine deaminase domain further comprises a wild-type adenosine deaminase domain; (z) the ABE8 is selected from the group consisting of: ABE8.1-m, ABE8.2-m, ABE8.3-m, ABE8.5-m, ABE8.8-m, ABE8.9-m, ABE8.10-m, ABE8.11-m, ABE8.12-m, ABE8.13-m, ABE8.14-m, ABE8.15-m, ABE8.16-m, ABE8.17-m, ABE8.18-m, ABE8.19-m, ABE8.20-m, ABE8.21-m, ABE8.22-m, ABE8.23-m, ABE8.24-m, ABE8.1-d, ABE8.2-d, ABE8.3-d, ABE8.5-d, ABE8.8-d, ABE8.9-d, ABE8.10-d, ABE8.11-d, ABE8.12-d, ABE8.13-d, ABE8.14-d, ABE8.15-d, ABE8.16-d, ABE8.17-d, ABE8.18-d, ABE8.19-d, ABE8.20-d, ABE8.21-d, ABE8.22-d, ABE8.23-d, and ABE8.24-d;(aa) the one or more guide RNAs comprises a CRISPR RNA (crRNA) and a trans-encoded small RNA (tracrRNA), wherein the crRNA comprises a nucleic acid sequence complementary to a G6PC nucleic acid sequence comprising the SNP associated with GSD1a;(bb) the base editor is in complex with a single guide RNA (sgRNA) comprising a nucleic acid sequence complementary to an G6PC nucleic acid sequence comprising the SNP associated with GSD1a;(cc) the guide polynucleotide is a gRNA comprising a scaffold having the following sequence: GUUUUAGAGCUAGAAAUAGCAAGUUAAAAUAAGGCUAGUCCGUUAUCAACUUGAAAAAGUGGCACCGAGUCGGUGCUUUU;(dd) the guide polynucleotide is a gRNA comprising a scaffold having the following sequence: GUUUUAGUACUCUGUAAUGAAAAUUACAGAAUCUACUAAAACAAGGCAAAAUGCCGUGUUUAUCUCGUCAACUUGUUGGCGAGAUUUU;(ee) the cell is a hepatocyte, a hepatocyte precursor, or an iPSc-derived hepatocyte;(ff) the cell expresses a G6PC polypeptide;(gg) the cell is from a subject having GSD1a;(hh) the cell is a mammalian cell; and2020221355   24 Apr 2026(ii) the cell is a human cell.

5. A method of treating GSD1a in a subject comprising administering to said subject:an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, wherein said ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; andone or more guide polynucleotides that target the ABE8 to effect an A»T to G»C alteration of the SNP associated with GSD1a, with the proviso that said administration is not made to a human ovum, a human zygote, a human embryo, or a human totipotent cell.

6. The method of claim 5, comprising one or more of:(a) the subject is a non-human mammal or a human;(b) the method comprises delivering the ABE8, or polynucleotide encoding said ABE8, and said one or more guide polynucleotides to a cell of the subject;(c) the method comprises delivering the ABE8, or polynucleotide encoding said ABE8, and said one or more guide polynucleotides to a cell of the subject and the cell is a hepatocyte, a hepatocyte precursor, or an iPSc-derived hepatocyte;(d) the SNP associated with GSD1a results in expression of a G6PC polypeptide that prematurely terminates at amino acid position 347 or comprises a cysteine at position 83;(e) the SNP encodes one or more of Q347X and R83C;(f) the polynucleotide programmable DNA binding domain is a Streptococcus pyogenes Cas9 (SpCas9) or variant thereof;(g) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having an altered protospacer-adjacent motif (PAM) specificity or specificity for a non-G PAM;2020221355   24 Apr 2026(h) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having specificity for the nucleic acid sequence 5’-NGA-3’;(i) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having specificity for the nucleic acid sequence 5’-AGA-3’ or 5’-GGA-3’;(j) the polynucleotide programmable DNA binding domain comprises a modified SpCas9 having specificity for an NGA PAM variant;(k) the polynucleotide programmable DNA binding domain is a Staphylococcus aureus Cas9 (SaCas9) or variant thereof;(l) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for the nucleic acid sequence 5’-NNGRRT-3’;(m) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for the nucleic acid sequence 5’-GAGAAT-3’;(n) the polynucleotide programmable DNA binding domain comprises a modified SaCas9 having specificity for an NNGRRT PAM variant;(o) the polynucleotide programmable DNA binding domain is a nuclease inactive variant;(p) the polynucleotide programmable DNA binding domain is a nickase variant;(q) the polynucleotide programmable DNA binding domain is a nickase variant and the nickase variant comprises an amino acid substitution D10A or a corresponding amino acid substitution thereof;(r) the adenosine deaminase domain is a monomer;(s) the adenosine deaminase domain further comprises a wild-type adenosine deaminase domain;(t) the adenosine deaminase variant further comprises an alteration selected from the group consisting of Y123H and Q154R;(u) the adenosine deaminase variant comprises a combination of alterations selected from the group consisting of:Y147T and Q154R;Y147T and Q154S;Y147R and Q154S;V82S and Q154S;V82S and Y147R;V82S and Q154R;2020221355   24 Apr 2026V82S and Y123H;I76Y and V82S;V82S, Y123H, and Y147T;V82S, Y123H, and Y147R;V82S, Y123H, and Q154R;Y147R, Q154R, and Y123H;Y147R, Q154R, and I76Y;Y147R, Q154R, and T166R;Y123H, Y147R, Q154R, and I76Y;V82S, Y123H, Y147R, and Q154R; and I76Y, V82S, Y123H, Y147R, and Q154R;(v) the adenosine deaminase variant comprises the alterations Y147T and Q154S;(w) the guide polynucleotide has a nucleic acid sequence selected from the group consisting of:a) GACCUAGGCGAGGCAGUAGG;b) CCAGUAUGGACACUGUCCAAA;c) CAGUAUGGACACUGUCCAAA; andd) AGUAUGGACACUGUCCAAAG;(x) the adenosine deaminase variant is a TadA deaminase;(y) the adenosine deaminase variant is a TadA deaminase and the TadA deaminase is selected from the group consisting of: TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.5, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, and TadA*8.24;(z) the Adenosine Deaminase Base Editor 8 (ABE8) is selected from the group consisting of: ABE8.1-m, ABE8.2-m, ABE8.3-m, ABE8.5-m, ABE8.8-m, ABE8.9-m, ABE8.10-m, ABE8.11-m, ABE8.12-m, ABE8.13-m, ABE8.14-m, ABE8.15-m, ABE8.16-m, ABE8.17-m, ABE8.18-m, ABE8.19-m, ABE8.20-m, ABE8.21-m, ABE8.22-m, ABE8.23-m, ABE8.24-m, ABE8.1-d, ABE8.2-d, ABE8.3-d, ABE8.5-d, ABE8.8-d, ABE8.9-d, ABE8.10-d, ABE8.11-d, ABE8.12-d, ABE8.13-d, ABE8.14-d, ABE8.15-d, ABE8.16-d, ABE8.17-d, ABE8.18-d, ABE8.19-d, ABE8.20-d, ABE8.21-d, ABE8.22-d, ABE8.23-d, and ABE8.24-d;2020221355   24 Apr 2026(aa) the one or more guide RNAs comprises a CRISPR RNA (crRNA) and a trans-encoded small RNA (tracrRNA), wherein the crRNA comprises a nucleic acid sequence complementary to a G6PC nucleic acid sequence comprising the SNP associated with GSD1a; and(bb) the base editor is in complex with a single guide RNA (sgRNA) comprising a nucleic acid sequence complementary to G6PC nucleic acid sequence comprising the SNP associated with GSD1.

7. A method of producing a hepatocyte, or progenitor thereof, the method comprising:(a) introducing into an induced pluripotent stem cell or hepatocyte progenitor comprising a SNP associated with GSD1a:an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding the ABE8, wherein the base editor comprises a polynucleotide-programmable nucleotide-binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; andone or more guide polynucleotides, wherein the one or more guide polynucleotides target the base editor to effect an A»T to G»C alteration of the SNP associated with GSDla; and(b) differentiating the induced pluripotent stem cell into a hepatocyte or progenitor thereof.

8. The method of claim 7, comprising one or more of:(a) the hepatocyte progenitor is obtained from a subject having GSD1a;(b) the hepatocyte or hepatocyte progenitor is a non-human mammalian cell or human cell;(c) the SNP associated with GSD1a changes a glutamine to a non-glutamine amino acid or changes an arginine to a non-arginine amino acid in the G6PC polypeptide;2020221355   24 Apr 2026(d) the SNP associated with GSD1a results in expression of an G6PC polypeptide having a nonglutamine amino acid at position 347 or a non-arginine amino acid at position 83;(e) the induced pluripotent stem cell of step (a) comprises a G6PC polypeptide comprising a Q347X mutation;(f) the induced pluripotent stem cell of step (a) comprises a G6PC polypeptide comprising a R83C mutation;(g) the adenosine deaminase domain is a monomer;(h) the adenosine deaminase domain further comprises a wild-type adenosine deaminase domain and an adenosine deaminase variant;(i) the adenosine deaminase variant comprises an alteration selected from the group consisting of Y123H and Q154R;(j) the adenosine deaminase variant comprises a combination of alterations selected from the group consisting of:Y147T and Q154R;Y147T and Q154S;Y147R and Q154S;V82S and Q154S;V82S and Y147R;V82S and Q154R;V82S and Y123H;I76Y and V82S;V82S, Y123H, and Y147T;V82S, Y123H, and Y147R;V82S, Y123H, and Q154R;Y147R, Q154R, and Y123H;Y147R, Q154R, and I76Y;Y147R, Q154R, and T166R;Y123H, Y147R, Q154R, and I76Y;V82S, Y123H, Y147R, and Q154R; andI76Y, V82S, Y123H, Y147R, and Q154R;(k) the adenosine deaminase variant comprises the alterations Y147T and Q154S;2020221355   24 Apr 2026(l) the guide polynucleotide comprises a nucleic acid sequence selected from the group consisting of:a) GACCUAGGCGAGGCAGUAGG;b) CCAGUAUGGACACUGUCCAAA;c) CAGUAUGGACACUGUCCAAA; andd) AGUAUGGACACUGUCCAAAG;(m) the adenosine deaminase variant is a TadA deaminase;(n) the adenosine deaminase variant is a TadA deaminase and the TadA deaminase is selected from the group consisting of: TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.5, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, and TadA*8.24;(o) the Adenosine Deaminase Base Editor 8 (ABE8) is selected from the group consisting of: ABE8.1-m, ABE8.2-m, ABE8.3-m, ABE8.5-m, ABE8.8-m, ABE8.9-m, ABE8.10-m, ABE8.11-m, ABE8.12-m, ABE8.13-m, ABE8.14-m, ABE8.15-m, ABE8.16-m, ABE8.17-m, ABE8.18-m, ABE8.19-m, ABE8.20-m, ABE8.21-m, ABE8.22-m, ABE8.23-m, ABE8.24-m, ABE8.1-d, ABE8.2-d, ABE8.3-d, ABE8.5-d, ABE8.8-d, ABE8.9-d, ABE8.10-d, ABE8.11-d, ABE8.12-d, ABE8.13-d, ABE8.14-d, ABE8.15-d, ABE8.16-d, ABE8.17-d, ABE8.18-d, ABE8.19-d, ABE8.20-d, ABE8.21-d, ABE8.22-d, ABE8.23-d, and ABE8.24-d;(p) the one or more guide RNAs comprises a CRISPR RNA (crRNA) and a trans-encoded small RNA (tracrRNA), wherein the crRNA comprises a nucleic acid sequence complementary to a G6PC nucleic acid sequence comprising the SNP associated with GSD1a; and(q) the base editor is in complex with a single guide RNA (sgRNA) comprising a nucleic acid sequence complementary to G6PC nucleic acid sequence comprising the SNP associated with GSD1.

9. A method of editing a glucose-6-phosphatase (G6PC) polynucleotide comprising a single nucleotide polymorphism (SNP) associated with Glycogen Storage Disease Type 1a (GSD1a), the method comprising contacting the G6PC polynucleotide with an Adenosine Deaminase Base Editor 8 (ABE8) in a complex with one or more guide polynucleotides, wherein the ABE8 comprises an adenosine deaminase domain inserted within a Cas9 or a Cas12 polypeptide,2020221355   24 Apr 2026wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and wherein one or more of said guide polynucleotides target said base editor to effect an A»T to G»C alteration of the SNP associated with GSD1a.

10. A method of treating Glycogen Storage Disease Type 1a (GSD1a) in a subject, themethod comprising administering to said subject:an Adenosine Deaminase Base Editor 8 (ABE8), or a polynucleotide encoding said base editor, wherein said ABE8 comprises an adenosine deaminase domain inserted within a Cas9 or Cas12 polypeptide, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence; andone or more guide polynucleotides that target the ABE8 to effect an A»T to G^C alteration of a SNP associated with GSD1a, thereby treating GSD1a in the subject, with the proviso that said administration is not made to a human ovum, a human zygote, a human embryo, or a human totipotent cell.

11. A method for treating Glycogen Storage Disease Type 1a (GSD1a) in a subject, the method comprising administering to the subject:2020221355   24 Apr 2026a fusion protein comprising an adenosine deaminase domain inserted within a Cas9 or a Cas12 polypeptide, or a polynucleotide encoding said fusion protein, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence;and one or more guide polynucleotides to target the fusion protein to effect an A»T to G^C alteration of a single nucleotide polymorphism (SNP) associated with GSD 1a, thereby treating GSD1a in the subject, with the proviso that said administration is not made to a human ovum, a human zygote, a human embryo, or a human totipotent cell.

12. The method of claim 9 or claim 10, wherein the Adenosine Deaminase Base Editor 8 (ABE8) is selected from the group consisting of: ABE8.1-m, ABE8.2-m, ABE8.3-m, ABE8.5-m, ABE8.8-m, ABE8.9-m, ABE8.10-m, ABE8.11-m, ABE8.12-m, ABE8.13-m, ABE8.14-m, ABE8.15-m, ABE8.16-m, ABE8.17-m, ABE8.18-m, ABE8.19-m, ABE8.20-m, ABE8.21-m, ABE8.22-m, ABE8.23-m, ABE8.24-m, ABE8.1-d, ABE8.2-d, ABE8.3-d, ABE8.5-d, ABE8.8-d, ABE8.9-d, ABE8.10-d, ABE8.11-d, ABE8.12-d, ABE8.13-d, ABE8.14-d, ABE8.15-d, ABE8.16-d, ABE8.17-d, ABE8.18-d, ABE8.19-d, ABE8.20-d, ABE8.21-d, ABE8.22-d, ABE8.23-d, and ABE8.24-d.

13. The method of any one of claims 9-12, comprising one or more of:(a) the adenosine deaminase variant further comprises a T166R amino acid alteration;(b) the adenosine deaminase variant further comprises an alteration selected from the group consisting of T166R, Y123H, and Q154R;(c) the adenosine deaminase variant comprises one of the following combinations of alterations:Y147T and Q154R;Y147T and Q154S;Y147R and Q154S;2020221355   24 Apr 2026V82S and Q154S;V82S and Y147R;V82S and Q154R;V82S and Y123H;I76Y and V82S;V82S, Y123H, and Y147T;V82S, Y123H, and Y147R;V82S, Y123H, and Q154R;Y147R, Q154R, and Y123H;Y147R, Q154R, and I76Y;Y147R, Q154R, and T166R;Y123H, Y147R, Q154R, and I76Y;V82S, Y123H, Y147R, and Q154R; and I76Y, V82S, Y123H, Y147R, and Q154R;(d) the adenosine deaminase variant is TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.5, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, and TadA*8.24;(e) the adenosine deaminase variant comprises a deletion of the C terminus beginning at a residue selected from the group consisting of 149, 150, 151, 152, 153, 154, 155, 156, and 157;(f) the adenosine deaminase domain is an adenosine deaminase monomer;(g) the adenosine deaminase domain further comprises a wild-type adenosine deaminase domain;(h) the adenosine deaminase domain further comprises a TadA domain;(i) the SNP associated with GSD1a is located in the glucose-6-phosphatase (G6PC) gene;(j) the SNP associated with GSD1a changes a glutamine (Q) to a non-glutamine amino acid or changes an arginine (R) to a non-arginine amino acid in an G6PC polypeptide;(k) the SNP associated with GSD1a results in expression of an G6PC polypeptide having a nonglutamine amino acid at position 347 or a non-arginine amino acid at position 83;(l) the A»T to OC alteration at the SNP associated with GSD1 a replaces the non-glutamine amino acid at position 347 with a glutamine or the non-arginine amino acid at position 83 with an arginine;2020221355   24 Apr 2026(m) the SNP associated with GSD1a results in expression of a G6PC polypeptide that prematurely terminates at amino acid position 347 or comprises a cysteine at position 83;(n) the SNP encodes one or more of Q347X and R83C;(o) the adenosine deaminase domain is inserted within a flexible loop, an alpha helix region, an unstructured portion, or a solvent accessible portion of the Cas9 or Cas12 polypeptide;(p) the adenosine deaminase domain is flanked by a N-terminal fragment and a C-terminal fragment of the Cas9 or Cas12 polypeptide;(q) the fusion protein or Adenosine Deaminase Base Editor 8 (ABE8) comprises the structure NH2-[N-terminal fragment of the Cas9 or Cas12 polypeptide]-[adenosine deaminase domain]-[C-terminal fragment of the Cas9 or Cas12 polypeptide]-COOH, wherein each instance of “]-[“ is an optional linker;(r) the one or more guide polynucleotides direct the fusion protein or ABE8 to effect deamination of a target nucleobase;(s) the fusion protein or ABE8 comprises a Cas9 polypeptide;(t) the adenosine deaminase domain is inserted in a Cas12 polypeptide;(u) the guide RNA comprises a CRISPR RNA (crRNA) and a trans-activating crRNA (tracrRNA) , wherein the crRNA comprises a nucleic acid sequence complementary to a G6PC nucleic acid sequence comprising the SNP associated with GSD1a; and(v) the subject is a non-human mammal or a human.

14. The method of claim 13, comprising one or more of:(a) the C-terminus of the N terminal fragment or the N-terminus of the C terminal fragment comprises a part of a flexible loop of the Cas9 or the Cas12 polypeptide;(b) the C-terminus of the N terminal fragment or the N-terminus of the C terminal fragment comprises a part of a flexible loop of the Cas9 or the Cas12 polypeptide and the flexible loop comprises an amino acid in proximity to a target nucleobase;(c) the deamination of the SNP target nucleobase replaces the target nucleobase with a non-wild type nucleobase, and wherein the deamination of the target nucleobase ameliorates symptoms of GSD1a;(d) the target nucleobase is 1-20 nucleobases away from a PAM sequence in the target polynucleotide sequence;2020221355   24 Apr 2026(e) the target nucleobase is 2-12 nucleobases upstream of the PAM sequence;(f) the N-terminal fragment or the C-terminal fragment of the Cas9 or Cas12 polypeptide binds the target polynucleotide sequence;(g) the N-terminal fragment or the C-terminal fragment comprises a RuvC domain;the N-terminal fragment or the C-terminal fragment comprises a HNH domain;neither of the N-terminal fragment and the C-terminal fragment comprises an HNH domain; or neither of the N-terminal fragment and the C-terminal fragment comprises a RuvC domain;(h) the Cas9 or Cas12 polypeptide comprises a partial or complete deletion in one or more structural domains and wherein the adenosine deaminase domain is inserted at the partial or complete deletion position of the Cas9 or Cas12 polypeptide;(i) the Cas9 or Cas12 polypeptide comprises a partial or complete deletion in one or more structural domains and wherein the adenosine deaminase domain is inserted at the partial or complete deletion position of the Cas9 or Cas12 polypeptide andthe deletion is within a RuvC domain;the deletion is within an HNH domain; orthe deletion bridges a RuvC domain and a C-terminal domain, a L-I domain and a HNH domain, or a RuvC domain and a L-I domain;(j) the Cas9 polypeptide is a Streptococcus pyogenes Cas9 (SpCas9), Staphylococcus aureus Cas9 (SaCas9), Streptococcus thermophilus 1 Cas9 (St1Cas9), or variants thereof;(k) the Cas9 polypeptide comprises the following amino acid sequence (Cas9 reference sequence):MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATRL KRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDEVAY HEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTY NQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSNF DLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTEITKAPLSAS MIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMD GTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRI PYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKVLPKHS LLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTVKQLKEDYFKKIECFD SVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYA2020221355   24 Apr 2026HLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTF KEDIQKAQVS GQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQ TTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINR LSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRK FDNLTKAERGGLSELDKAGFIKRQLvETRQiTKHVAQiLSSRMNTKYSENSKLIREVKVZTLKS KLVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRKMIAK SEQEIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLS MPQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKG KSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLAS AGELQKGNELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRV ILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLD ATLIHQSITGLYETRIDLSQLGGD (single underline: HNH domain; double underline: RuvC domain);(l) the Cas9 polypeptide comprises a deletion of amino acids 1017-1069 as numbered in the Cas9 polypeptide reference sequence or corresponding amino acids thereof;the Cas9 polypeptide comprises a deletion of amino acids 792-872 as numbered in the Cas9 polypeptide reference sequence or corresponding amino acids thereof; orthe Cas9 polypeptide comprises a deletion of amino acids 792-906 as numbered in the Cas9 polypeptide reference sequence or corresponding amino acids thereof;(m) the adenosine deaminase domain is inserted within a flexible loop of the Cas9 polypeptide;(n) the C-terminus of the N terminal fragment or the N-terminus of the C terminal fragment comprises a part of a flexible loop of the Cas9 or the Cas12 polypeptide and the flexible loop comprises a region selected from the group consisting of amino acid residues at positions 530537, 569-579, 686-691, 768-793, 943-947, 1002-1040, 1052-1077, 1232-1248, and 1298-1300 as numbered in the Cas9 reference sequence, or corresponding amino acid positions thereof;(o) the adenosine deaminase domain is inserted between amino acid positions 768-769, 791-792, 792-793, 1015-1016, 1022-1023, 1026-1027, 1029-1030, 1040-1041, 1052-1053, 1054-1055, 1067-1068, 1068-1069, 1247-1248, or 1248-1249 as numbered in the Cas9 reference sequence, or corresponding amino acid positions thereof;2020221355   24 Apr 2026(p) the adenosine deaminase domain is inserted between amino acid positions 768-769, 792-793, 1022-1023, 1026-1027, 1040-1041, 1068-1069, or 1247-1248 as numbered in the Cas9 reference sequence, or corresponding amino acid positions thereof;(q) the adenosine deaminase domain is inserted between amino acid positions 1016-1017, 10231024, 1029-1030, 1040-1041, 1069-1070, or 1247-1248 as numbered in the Cas9 reference sequence, or corresponding amino acid positions thereof;(r) the adenosine deaminase domain is inserted within the Cas9 polypeptide at the loci identified in Table 10A;(s) the N-terminal fragment comprises amino acid residues 1-529, 538-568, 580-685, 692-942, 948-1001, 1026-1051, 1078-1231, and / or 1248-1297 of the Cas9 reference sequence, or corresponding residues thereof;(t) the C-terminal fragment comprises amino acid residues 1301-1368, 1248-1297, 1078-1231, 1026-1051, 948-1001, 692-942, 580-685, and / or 538-568 of the Cas9 reference sequence, or corresponding residues thereof;(u) the Cas9 polypeptide is a nickase or wherein the Cas9 polypeptide is nuclease inactive;(v) the Cas9 polypeptide is a modified SpCas9 and has specificity for an altered PAM or specificity for a non-G PAM;(w) the Cas9 polypeptide is a modified SpCas9 polypeptide including amino acid substitutions D1135M, S1136Q, G1218K, E1219F, A1322R, D1332A, R1335E, and T1337R (SpCas9-MQKFRAER) and has specificity for the altered PAM 5’-NGC-3’;(x) the Cas12 polypeptide is Cas12a, Cas12b, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i;(y) the adenosine deaminase domain is inserted between amino acid positions:a) 153-154, 255-256, 306-307, 980-981, 1019-1020, 534-535, 604-605, or 344-345 of BhCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i;b) 147 and 148, 248 and 249, 299 and 300, 991 and 992, or 1031 and 1032 of BvCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i; or2020221355   24 Apr 2026c) 157 and 158, 258 and 259, 310 and 311, 1008 and 1009, or 1044 and 1045 of AaCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i;(z) the adenosine deaminase domain is inserted within the Cas12 polypeptide at the loci identified in Table 10B;(aa) the Cas12 polypeptide is Cas12b; and(bb) the Cas12 polypeptide comprises a BhCas12b domain, a BvCas12b domain, or an AACas12b domain.

15. A pharmaceutical composition for the treatment of Glycogen Storage Disease Type 1a (GSD1a) comprising an effective amount of an Adenosine Deaminase Base Editor 8 (ABE8), wherein said ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence.

16. The pharmaceutical composition of claim 15, including one or more of:(a) the pharmaceutical composition further comprising one or more guide polynucleotides that are capable of targeting the ABE8 to effect an A»T to G^C alteration of a SNP associated with GSD1a;(b) the adenosine deaminase domain is inserted within the polynucleotide programmable DNA binding domain; and(c) the Adenosine Deaminase Base Editor 8 (ABE8) is selected from the group consisting of: ABE8.1-m, ABE8.2-m, ABE8.3-m, ABE8.5-m, ABE8.8-m, ABE8.9-m, ABE8.10-m, ABE8.11-m, ABE8.12-m, ABE8.13-m, ABE8.14-m, ABE8.15-m, ABE8.16-m, ABE8.17-m, ABE8.18-m, ABE8.19-m, ABE8.20-m, ABE8.21-m, ABE8.22-m, ABE8.23-m, ABE8.24-m, ABE8.1-d,2020221355   24 Apr 2026ABE8.2-d, ABE8.3-d, ABE8.5-d, ABE8.8-d, ABE8.9-d, ABE8.10-d, ABE8.11-d, ABE8.12-d, ABE8.13-d, ABE8.14-d, ABE8.15-d, ABE8.16-d, ABE8.17-d, ABE8.18-d, ABE8.19-d, ABE8.20-d, ABE8.21-d, ABE8.22-d, ABE8.23-d, and ABE8.24-d.

17. A pharmaceutical composition for the treatment of Glycogen Storage Disease Type 1a (GSD1a) comprising an effective amount of the cell of claim 3 or claim 4.

18. The pharmaceutical composition of any one of claims 15-17, further comprising a pharmaceutically acceptable excipient.

19. A kit for the treatment of Glycogen Storage Disease Type 1a (GSD1a), the kit comprising an Adenosine Deaminase Base Editor 8 (ABE8), wherein said ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and one or more guide polynucleotides that are capable of targeting the ABE8 to effect an A»T to OC alteration of a SNP associated with GSD1a.

20. A kit for the treatment of Glycogen Storage Disease Type 1a (GSD1a), the kit comprising the cell of claim 3 or claim 4.

21. A base editor system comprising an Adenosine Deaminase Base Editor 8 (ABE8) in a complex with one or more guide polynucleotides, wherein the ABE8 comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain, wherein the adenosine deaminase domain comprises an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:2020221355   24 Apr 2026MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and wherein one or more of said guide polynucleotides target said base editor to effect an A»T to OC alteration of the SNP associated with GSD1a.

22. The base editor system of claim 21, comprising one or more of:(a) the adenosine deaminase variant comprises the V82S alteration and / or a T166R alteration; (b) the adenosine deaminase variant further comprises one or more of the alterations Y123H and Q154R;(c) the adenosine deaminase domain further comprises a wild-type adenosine deaminase domain; (d) the adenosine deaminase variant is truncated missing 1, 2, 3, 4, 5 ,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 N-terminal amino acid residues relative to the full length reference amino acid sequence;(e) the adenosine deaminase variant is truncated missing 1, 2, 3, 4, 5 ,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 C-terminal amino acid residues relative to the full length reference amino acid sequence;(f) the polynucleotide programmable DNA binding domain is a Staphylococcus aureus Cas9 (SaCas9), Streptococcus thermophilus 1 Cas9 (St1Cas9), a Streptococcus pyogenes Cas9 (SpCas9), or variants thereof;(g) the polynucleotide programmable DNA binding domain is a variant of SpCas9 having an altered protospacer-adjacent motif (PAM) specificity or specificity for a non-G PAM;(h) the polynucleotide programmable DNA binding domain is a nuclease inactive Cas9; and (i) the polynucleotide programmable DNA binding domain is a Cas9 nickase.

23. A base editor system comprising one or more guide RNAs and a fusion protein comprising a polynucleotide programmable DNA binding domain comprising an amino acid sequence with at least 90% identity to the following sequence:2020221355   24 Apr 2026DKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEATRLK RTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDEVAYH EKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYN QLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSNFD LAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTEITKAPLSASM IKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDG TEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIP YYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKVLPKHSL LYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTVKQLKEDYFKKIECFDS VEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYAH LFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTFK EDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQT TQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRL SDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKF DNLTKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNTKYDENDKLIREVKVITLKSK LVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRKMIAKS EQEIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSM PQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGK SKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASA GELQKGNELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVI LADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDA TLIHQSITGLYETRIDLSQLGGD, and at least one base editor domain comprising an adenosine deaminase variant comprising an amino acid sequence that is at least 90% identical to the following reference amino acid sequence:MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMALR QGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYPGMNH RVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD, wherein the adenosine deaminase variant further comprises an amino acid alteration selected from the group consisting of V82S, Y147T, Y147R, and Q154S relative to the reference amino acid sequence, and wherein one or more of said guide polynucleotides target said base editor to effect an A»T to OC alteration of the SNP associated with GSD1a.2020221355   24 Apr 202624. A cell comprising the base editor system of any one of claims 21-23, with the proviso that the cell is not a human ovum, a human zygote cell, a human embryo cell, or a human totipotent cell.

25. The cell of claim 24, comprising one or more of:(a) the cell is a human cell or a non-human mammalian cell; and(b) the cell is ex vivo, in vivo, or in vitro.

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