The clinical diagnosis of STGD1 is further complicated by phenotypic overlaps with Malattia Levantinese, pattern macular dystrophy, enhanced S-cone syndrome, achromatopsia, Stargardt-like diseases (STGD3 and STGD4), and, in severe cases, CORD and RP. The gene discussed is ABCA4; the disease is retinitis pigmentosa 1.