RHODOPSIN C110Y MUTATION CAUSES A TYPE-2 AUTOSOMAL-DOMINANT RETINITIS-PIGMENTOSA

Purpose: The RHO C110Y mutation has been recently reported to cause a phenotypically unspecified form of autosomal dominant retinitis pigmen tosa (adRP), The study of a family affected with this mutation allowed us to hereby describe the genotype/phenotype correlation associated w ith the RHO C110Y mutation. Methods: A six-generation pedigree cosegre gating adRP and RHO C110Y in ten accessible individuals was ophthalmol ogically investigated. All family members affected with RP went throug h complete eye examination and ERC testing. Results: The disease first manifested with nyctalopia during adulthood and slowly progressed ove r the next decades towards tubular visual field defects and relatively preserved central vision. Ophthalmoscopically, the fundus remained al most unaltered until the end of the third decade of life, and then slo wly progressed towards typical RP changes with minimal macular involve ment by the eighth decade. Color vision remained unaltered. Earliest E RG alteration was limited to the rod system followed by a rod-cone pat tern. Scotopic and photopic ERG were recordable until the fourth and s ixth decades, respectively. Discussion: RHO C110Y-associated adRP is c haracterized by a late onset and a mild progression compatible with ty pe 2 or regional RP with little intrafamilial phenotypic variability a nd complete penetrance. Characterization of genotype-phenotype correla tions plays a role in the improvement of genetic and prognostic counse lling.