HETEROZYGOUS MISSENSE MUTATION IN THE RHODOPSIN GENE AS A CAUSE OF CONGENITAL STATIONARY NIGHT BLINDNESS

A number of mutations in the rhodopsin gene have been shown to cause b oth dominant and recessive retinitis pigmentosa. Here we describe anot her phenotype associated with a defect in this gene. We discovered a p atient with congenital stationary night blindness who carries the miss ense mutation Ala292Glu. When coupled with 11-cis-retinal in vitro, Al a292Glu rhodopsin is able to activate transducin in a light-dependent manner like wild-type rhodopsin. However, without a chromophore, Ala29 2Glu opsin anomalously activates transducin. We speculate that the rod dysfunction in this patient is due to an abnormal, continuous activat ion of transducin by mutant opsin molecules in photoreceptor outer seg ments.