RP2 and retinitis pigmentosa 1: The prevalence of RP is estimated to be 1:3000, with 30%–40% of cases inherited via an autosomal dominant retinitis pigmentosa, 45%–60% via an autosomal recessive route (ADRP), and 5%–15% as an X-linked (XL) trait.1, 2, 3, 4, 5RPGR mutations account for 70%–80% of XLRP6, 7, 8 with RP2 variants accounting for a further 6%–20%.7, 8, 9, 10, 11RPGR-associated RP is particularly severe, with an early onset of disease in childhood.