Abstract
Abstract: :
Purpose: Using a differential cloning strategy, we have isolated a new gene, HRG5, which is expressed highly in the retina. This gene has turned out to be the regulator of G-protein signaling 9 (RGS9), an accelerator of GTPase that aids in the deactivation of transducin in phototransduction. The function of this gene and its chromosomal location, 17q24 where RP17 maps, suggest that HRG5 (RGS9) may be a good candidate for retinal degeneration. We have begun to screen this gene for mutations in patients with retinal diseases. Methods: The 17 exons in the HRG5 (RGS9) gene were elucidated. Initially, forty-nine autosomal dominant retinitis pigmentosa (ADRP) patients were screened for mutations. The exonic sequences were PCR-amplified from their DNA and subjected to heteroduplex analysis. Eighty autosomal recessive retinitis pigmentosa (ARRP) patients are also beginning to be screened. Results: From the 49 ADRP patients screened, five variants were discovered. All were intronic. Alterations included: IVS12+51A-≷G, IVS13+32insT, IVS15+22A-≷G, IVS16+83A-≷G, and IVS16+100del 8 bp. The allele frequencies of the variants were 4%, 1%, 4%, 4%, and 1%, respectively, in our patients. Conclusion: Although HRG5 (RGS9) is likely to be a good candidate for retinal degeneration, we did not uncover any obvious disease-related mutations in our ADRP patients. The number of ADRP patients screened, however, was small, and further analysis of ARRP and other retinopathy patients may reveal a significant sequence change.
Keywords: 420 genetics • 480 mutations • 562 retinal degenerations: hereditary