The GUCY2D encodes the membrane bound retinal guanylyl cyclase-1 protein (RetGC-1) which is a member of the membrane guanylyl cyclase family. It is expressed in both cone and rod photoreceptors, but predominantly in the cone outer segments. GUCY2D plays an essential role in normal vision, since it is responsible for a chemical reaction that helps return photoreceptors to their resting state after light exposure. Defects in this protein result in Leber congenital amaurosis 1 and cone-rod dystrophy-6 diseases.
LCA 1 is a severe dystrophy of the retina, presenting typically in the first years of life. The phenotype of LCA patients with mutations in this gene is that of a severe cone-rod dystrophy with photophobia and hyperopia.