Supplementing wildtype copies of functionally defective genes with adeno-associated virus (AAV) is a strategy being explored clinically for various retinal dystrophies. However, the low cargo limit of this vector allows its use in only a fraction of patients with mutations in relatively small pathogenic genes. To overcome this issue, we developed a single AAV platform that allows local replacement of a mutated sequence with its wildtype counterpart, based on combined CRISPR-Cas9 and micro-homology-mediated end-joining (MMEJ). In blind mice, the mutation replacement rescued approximately 10% of photoreceptors, resulting in an improvement in light sensitivity and an increase in visual acuity. These effects were comparable to restoration mediated by gene supplementation, which targets a greater number of photoreceptors. This strategy may be applied for the treatment of inherited disorders caused by mutations in larger genes, for which conventional gene supplementation therapy is not currently feasible.

中文翻译：

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有限数量的感光器中的单个AAV介导的突变替代基因组编辑可恢复小鼠的视力。

用腺相关病毒（AAV）补充功能缺陷基因的野生型拷贝是一种针对各种视网膜营养不良的临床研究方法。但是，该载体的低载量限制使其仅可用于一部分致病基因相对较小的突变患者。为了克服这个问题，我们基于CRISPR-Cas9和微同源介导的末端连接（MMEJ），开发了一个单一的AAV平台，该平台可以用其野生型对应物局部取代突变序列。在盲小鼠中，突变替换挽救了约10％的感光细胞，从而提高了光敏性并提高了视敏度。这些效果与基因补充介导的修复相当，后者针对的是更多的感光细胞。