CRISPR-Cas9–mediated therapeutic editing of <i>Rpe65</i> ameliorates the disease phenotypes in a mouse model of Leber congenital amaurosis

Leber congenital amaurosis (LCA), one of the leading causes of childhood-onset blindness, is caused by autosomal recessive mutations in several genes including <i>RPE65</i>. In this study, we performed CRISPR-Cas9-mediated therapeutic correction of a disease-associated nonsense mutation in <i>Rpe65</i> in <i>rd12</i> mice, a model of human LCA. Subretinal injection of adeno-associated virus carrying CRISPR-Cas9 and donor DNA resulted in >1% homology-directed repair and ~1.6% deletion of the pathogenic stop codon in <i>Rpe65</i> in retinal pigment epithelial tissues of <i>rd12</i> mice. The a- and b-waves of electroretinograms were recovered to levels up to 21.2 ± 4.1% and 39.8 ± 3.2% of their wild-type mice counterparts upon bright stimuli after dark adaptation 7 months after injection. There was no definite evidence of histologic perturbation or tumorigenesis during 7 months of observation. Collectively, we present the first therapeutic correction of an <i>Rpe65</i> nonsense mutation using CRISPR-Cas9, providing new insight for developing therapeutics for LCA.