Autosomal recessive childhood-onset severe retinal dystrophy is a heterogeneous group of disorders affecting rod and cone photoreceptors simultaneously. The most severe cases are termed Leber congenital amaurosis (LCA), whereas the less aggressive forms are usually considered juvenile retinitis pigmentosa. Various intermediate phenotypes between LCA and retinitis pigmentosa are known and are sometimes described as 'early-onset severe rod-cone dystrophy' or 'early-onset retinal degeneration'. [From OMIM]