Indel

Base pair

Biology

Nonsense mutation

Gene

Genetic enhancement

Genotype

Genome editing

Single-nucleotide polymorphism

Molecular biology

Point mutation

Transcription activator-like effector nuclease

Mutation

RPE65

Retinal

Missense mutation

CRISPR

Genetics

Biochemistry

Nature Biomedical Engineering

Cytosine base editors and adenine base editors (ABEs) can correct point mutations predictably and independent of Cas9-induced double-stranded DNA breaks (which causes substantial indel formation) and homology-directed repair (which typically leads to low editing efficiency). Here, we show, in adult mice, that a subretinal injection of a lentivirus expressing an ABE and a single-guide RNA targeting a de novo nonsense mutation in the Rpe65 gene corrects the pathogenic mutation with up to 29% efficiency and with minimal formation of indel and off-target mutations, despite the absence of the canonical NGG sequence as a protospacer-adjacent motif. The ABE-treated mice displayed restored RPE65 expression and retinoid isomerase activity, and near-normal levels of retinal and visual functions. Our findings motivate the further testing of ABEs for the treatment of inherited retinal diseases and for the correction of pathological mutations with non-canonical protospacer-adjacent motifs. Subretinal viral delivery, in mice, of an adenine base editor and a single-guide RNA targeting a nonsense mutation in the Rpe65 gene restores near-normal levels of retinal and visual functions.

Restoration of visual function in adult mice with an inherited retinal disease via adenine base editing