Leber Congenital Amaurosis (LCA) is a diagnosis for a group of severe, autosomal recessively inherited rod - cone dystrophies that typically result in complete visual loss in the third or fourth decade of life. One form, LCA2, is caused by a mutation in the gene encoding RPE56, an RPE-specific 65-kDa isomerase. Non-functional RPE65 results in photoreceptor cells that are unable to respond to light resulting in these patients being visually impaired.