Retinoid isomerohydrolase (RPE65) plays a pivotal role in the visual cycle, and functional impairments are known to cause severe forms of inherited retinal degenerations (IRDs), such as Leber congenital amaurosis 2 (LCA2; OMIM#204100) and retinitis pigmentosa (RP; OMIM#613791 and OMIM#618697). This evidence concerns the gene RPE65 and retinitis pigmentosa.