Cone-Rod Dystrophy, Intrafamilial Variability, and Incomplete Penetrance Associated with the R172W Mutation in the Peripherin/RDS Gene

The Arg172Trp (R172W) peripherin/RDS mutation has been previously reported to cause a fully penetrant progressive macular dystrophy with high intrafamilial and interfamilial consistency of phenotype. This is the first report describing marked intrafamilial variation associated with this mutation, including nonpenetrance. These findings are clinically important in relation to advice on prognosis and accurate genetic counseling.