ABCA4 Base Editing for Stargardt Mutation Correction
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Solution Overview
Problem
There are currently no effective treatments for Stargardt disease, a rare genetic eye disorder characterized by macular degeneration and progressive vision loss, primarily affecting the ABCA4 gene's function.
Innovation Solution
Utilizing an adenosine deaminase base editor to edit specific nucleobases in the ABCA4 gene, such as c.4139T to c.4139C and c.5714+5A to c.5714+5G, to correct pathogenic mutations and restore normal gene function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base editing is used to correct pathogenic mutations in ABCA4 gene, then treatment effectiveness is improved, but device complexity increases
Solution Approach 1:
The base editor system is divided into distinct functional modules: a nucleic acid programmable DNA binding protein domain (e.g., Cas9 variant) that targets the ABCA4 gene locus, and an adenosine deaminase domain that catalyzes the A-to-G conversion. This segmentation allows independent optimization of targeting specificity and editing efficiency while simplifying the overall system architecture.
Solution Approach 2:
A guide polynucleotide serves as an intermediary component that bridges the targeting function (DNA binding protein) and the editing function (adenosine deaminase). The guide RNA directs the base editor to the specific c.4139T or c.5714+5A nucleotide in the ABCA4 gene, enabling precise location identification without requiring the DNA binding protein to directly recognize the target sequence.
2Reliability
If adenosine deaminase base editor is applied to treat Stargardt disease, then patient outcome is improved, but manufacturing complexity increases
Solution Approach 1:
The base editor system is designed with universal components that can be adapted to treat different ABCA4 mutations. The same adenosine deaminase domain and DNA binding protein framework can target multiple nucleotide positions by simply changing the guide polynucleotide sequence, enabling a single manufacturing platform to produce editors for various mutation sites (e.g., c.4139T, c.5714+5A) without requiring entirely separate production lines.
Solution Approach 2:
The system allows easy adjustment of editing parameters through guide polynucleotide design. By modifying the guide RNA sequence to match different target sites in the ABCA4 gene, the same base editor construct can be redirected to correct various pathogenic mutations. This parameter-based customization simplifies manufacturing compared to developing entirely new editor proteins for each mutation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively alters the ABCA4 gene, potentially slowing or stabilizing progressive vision loss in patients with Stargardt disease.
Implementation Method 1
The base editor system also contains (b) one or more guide polynucleotides, or one or more polynucleotides encoding the guide polynucleotides, that target the base editor to effect a deamination of the adenosine (A) complementary to the c.4139T nucleobase
Data Source
AI summary
Compositions and methods for editing a pathogenic ATP-binding cassette, subfamily A, member 4 (ABCA4) polypeptide-encoding gene using an adenosine deaminase base editor to treat a congenital eye disorder, such as Stargardt disease. In various embodiments, the disclosure provides methods for altering a nucleobase (e.g., c.4139T) in an ABCA4 gene codon 1380 encoding a pathogenic leucine so that the codon is altered to encode a proline. In some embodiments, the disclosure provides methods for altering a pathogenic c.5714+5A intronic nucleotide of anABCA4 gene so that the nucleotide becomes c.5714+5G.