The X chromosome harbors a number of disease loci that affect the retina, including cone dystrophy (COD1 and COD2), juvenile retinoschisis (XLRS), congenital stationary night blindness (CSNB), and at least five loci for retinitis pigmentosa (Table 1, ref [18, 19-35]). The gene discussed is COG6; the disease is X-linked retinoschisis.