[MIM*204000 & MIM*204100] a disorder of cone-rod abiotrophy causing blindness or severely reduced vision at birth; autosomal recessive inheritance with at least three different loci. Type I is caused by mutation in the gene for retinal guanylate cyclase (GUC2D) on chromosome 17p, type II by mutation in the gene for retinal pigment epithelium-specific 65-kD protein (RPE65) on 1p, and type III by mutation in the gene for photoreceptor-specific homeobox gene CRX on 19q.