Rhodopsin Replacement in a I307N Mouse Model of ADRP by the Homology Independent Transgene Insertion Method

Abstract

Retinitis pigmentosa affects 1 in 4,000 people worldwide. Mutations in over twenty genes cause autosomal dominant retinitis pigmentosa. 30-40% of autosomal dominant retinitis pigmentosa are due to mutations rhodopsin with more than 100 known mutations being identified. Due to this allelic and causal diversity, allele-independent approaches are an attractive option. Here, we demonstrate an allele-independent CRISPR/Cas9 approach; this contrasts with many current allele-specific rhodopsin approaches. A homology-independent transgene is co-delivered with RSV-spCas9 packaged in an AAV5 vector for gene replacement via insertion in the Rho I307N mouse model of autosomal dominant retinitis pigmentosa. First, we establish the safety of this system, in C57BL/6J mice, demonstrating no loss of retinal thickness or function. We further show that outer nuclear layer thickness, electrical response, and rhodopsin expression in heterozygous Rho I307N were significantly preserved six months after treatment. This retention results from a 5.7% transgene integration and 88% indel rate in treated animals.