Exon screening of the genes encoding the beta- and gamma-subunits of cone transducin in patients with inherited retinal disease.

PURPOSE: To screen the exons of the genes encoding the beta3-subunit (GNB3) and gammac-subunit (GNGT2) of cone transducin for mutations in a large number of unrelated patients with various forms of inherited retinal disease including cone dystrophy, cone-rod dystrophy and macular dystrophy.
METHODS: Exons of the two genes were screened for mutations by denaturing gradient gel electrophoresis (DGGE) and/or single strand conformation polymorphism electrophoresis (SSCP); any variants were sequenced directly.
RESULTS: Although many sequence variants were found in both genes, none could be associated with disease. Additionally, the gene structure and sequence of the coding exons of GNB3 were determined and compared with those of the dog homolog. Both human and canine GNB3 have nine coding exons and their two predicted amino acid sequences have 97% identity.
CONCLUSIONS: The results indicate that GNB3 and GNGT2 are unlikely sites of mutations responsible for inherited retinal degenerations that predominantly effect cone-mediated function (cone and cone-rod dystrophies) or have a predilection for disease in the macula (macular dystrophies).