E2F3 and retinitis pigmentosa 1: For the possible connection with RP, it is interesting to note that YY1 can interact with HDACs, is itself regulated by acetylation,23 and may be photoreceptor specific in the retina.24 E2F3, on the other hand, might contribute to rod photoreceptor cell death in the rd1 model.25 Furthermore, NRL mutations are associated with autosomal-dominant RP.26 We thus analyzed the methylation status of potential YY1, E2F3, and NRL target genes (Supplementary Table S3).