Retinitis Pigmentosa (Non-syndromic).

Most of the genes causing autosomal recessive retinitis pigmentosa (AR-RP) are rare and cause 1% of all cases. Some of the genes, like PDE6 (PDE6A, PDE6B, PDE6G), RP25, and RPE65, have higher prevalence, about 2-5% of all cases. Overall, autosomal recessive RP accounts for about 15-20% of all cases of RP. Clinically, it shows all the classic features of RP, such as attenuated retinal blood vessels, intraretinal pigmentation, waxy pallor of the optic disc, and hyperfluorescent rings on fundus autofluorescence (FAF) (Figs. 25.1, 25.2 and 25.3). The ring is suggestive of increased metabolic burden of the corresponding retinal pigment epithelium (RPE).