THR4LYS RHODOPSIN MUTATION IS ASSOCIATED WITH AUTOSOMAL-DOMINANT RETINITIS-PIGMENTOSA OF THE CONE-ROD TYPE IN A SMALL DUTCH FAMILY

A mother and daughter with autosomal dominant retinitis pigmentosa (ad RP) were found to carry a cytosine-to-adenine transversion mutation at codon 4 of the rhodopsin gene. This mutation predicts a substitution of lysine for threonine at one of the glycosylation sites in the rhodo psin molecule (Thr4Lys). Both patients presented with a similar phenot ype including a tigroid pattern of the posterior pole and a regional p redilection for degenerative pigmentary changes in the inferior retina with corresponding visual field defects. The electroretinographic pat tern was suggestive of RP of the cone-rod type. This report documents the clinical findings associated with this defined mutation of the rho dopsin gene.