The X-linked genes in both cohorts included RPGR (associated with RP or cone–rod dystrophy), RS1 (associated with X-linked retinoschisis), CHM (choroideremia), CACNA1F (incomplete congenital stationary night blindness), RP2 (associated with RP), NYX (complete congenital stationary night blindness), and NDP (associated with Norrie disease or X-linked familial exudative vitreoretinopathy). The gene discussed is NDP; the disease is choroideremia.