To date, at least 65 different genes have been identified for the autosomal dominant (adRP), autosomal recessive (arRP), and X-linked (XLRP) forms of RP: 22 for adRP, 40 for arRP, and 3 for XLRP (retinitis pigmentosa GTPase regulator [RPGR], RP2 and OFD1). Here, RPGR is linked to retinitis pigmentosa 1.