Mutation of the RPE65 allele has been found to destroy optic cells and cause clinical manifestations of Leber congenital amaurosis type 2 (LCA2) and early-onset retinal dystrophy, eventually leading to complete blindness (Gu et al., 1997; Marlhens et al., 1997; Aguirre et al., 1998). The gene discussed is RPE65; the disease is Leber congenital amaurosis 2.