VISUAL FUNCTION IN RETINITIS-PIGMENTOSA RELATED TO A CODON-15 RHODOPSIN GENE MUTATION

To determine the phenotype of a Japanese family in which retinitis pig mentosa cosegregates with a rhodopsin gene mutation, i.e. an asparagin e-to-serine change at codon 15 (Asn-15-Ser), 5 affected and 5 unaffect ed members of one pedigree underwent several ophthalmic examinations a s well as Ganzfeld electroretinography (ERG) and multifocal ERG. Genom ic DNA samples were analyzed by PCR amplification, sequencing and rest riction enzyme digestion. A codon 15 rhodopsin gene mutation (Asn-15-S er) was found in all affected members. The region of pigmentary degene ration was localized in the lower hemiretina, and visual field defects corresponded to the retinal pigmentary changes. Scotopic ERG amplitud es, rather than photopic ERG amplitudes, were reduced. Multifocal ERG revealed a low magnitude of response density, even for the upper hemir etina, which showed no bony corpuscle pigmentation. Visual function in sectorial retinitis pigmentosa associated with rhodopsin gene codon 1 5 mutation is on the basis of the rod-cone dystrophy, regardless of di fferences in phenotypic expression.