RPE65 and retinitis pigmentosa 1: In addition, RP is also caused by mutations of genes expressed in the photoreceptor supporting tissue, i.e. the retinal pigment epithelium (RPE), the encoded proteins being involved in the retinol metabolism (the retinol isomerase RPE65, the 11-cis retinoid transporter CRALBP, the lecithin retinol acyl transferase LRAT, RGR) or in the phagocytosis of the photoreceptor outer segments (cMERTK).