Genotype-functional-phenotype correlations in photoreceptor guanylate cyclase (GC-E) encoded by GUCY2D

Publication date: March 2018Source: Progress in Retinal and Eye Research, Volume 63Author(s): Dror Sharon, Hanna Wimberg, Yael Kinarty, Karl-Wilhelm KochAbstractThe GUCY2D gene encodes for the photoreceptor guanylate cyclase GC-E that synthesizes the intracellular messenger of photoreceptor excitation cGMP and is regulated by intracellular Ca2+-sensor proteins named guanylate cyclase-activating proteins (GCAPs). Over 140 disease-causing mutations have been described so far in GUCY2D, 88% of which cause autosomal recessive Leber congenital amaurosis (LCA) while heterozygous missense mutations cause autosomal dominant cone-rod degeneration (adCRD). Mutations in GUCY2D are one of the major causes of all LCA cases and are the major cause of adCRD. A single amino acid, arginine at position 838, is likely to be the most sensitive one in GC-E as four single mutations and two complex mutations were reported to affect R838.The biochemical effect of 45 GC-E variants was studied showing a clear genotype-phenotype correlation: LCA-causing mutations either show reduced ability or complete inability to synthesize cGMP from GTP, while CRD-causing mutations are functional, but shift the Ca2+-sensitivity of the GC-E − GCAP complex.Eight animal models of retinal guanylate cyclase deficiency have been reported including knockout (KO) mouse and chicken models. These two models were used for gene augmentation therapy that yielded promising results.Here we integrate the available information on...
Source: Progress in Retinal and Eye Research - Category: Opthalmology Source Type: research