In fact, the majority of genetically solved X-linked RP can be explained by causative mutations in RPGR and RP2 genes accounting, respectively, for 75–80% and 10–15% of the genetically-solved cases of the disease1, 5, 6, 7, 8, 9, 10, 11. The gene discussed is RPGR; the disease is retinitis pigmentosa 1.