To attempt productive editing of the photoreceptors, a major therapeutic target for inherited retinal degenerations (IRDs), we then packaged CAG-promoter-expressed SpCas9 PEmax and the U6-promoter-expressed tdT-PRIDICT-epegRNA into dual-AAV2/8 vectors in a previously described architecture (SI Appendix, Fig. S4), as the serotype is known to efficiently transduce RPE, photoreceptors, and Müller glia (1:1 ratio, 2.5 × 109 viral genomes each) (35, –37). Here, DNTT is linked to respiratory distress syndrome in premature infants.