PRPF31 and retinitis pigmentosa 1: Our CRISPR/Cas9 KI approach in patient iPSCs demonstrated that insertion of a functional copy of PRPF31 into a specific safe locus of iPSCs from PRPF31 RP patients restored the expression levels of the PRPF31 protein and totally prevented the defective phenotype of RPE cells and photoreceptors in retinal organoids.