Polymorphism at codon 129 or codon 219 of PRNP and clinical heterogeneity in a previously unreported family with Gerstmann-Sträussler-Scheinker disease (PrP-P102L mutation).

We present a new, large, Italian family affected by Gerstmann-Sträussler-Scheinker syndrome (GSS) associated with the Pro to Leu point mutation at codon 102 of the prion protein gene (PRNP). The affected members of this family show a remarkable phenotypic variability of the disease: three of them had a clinical picture characterized by dementia and a brief illness duration (less than 1 year), while the other five members presented an ataxic, slowly evolving syndrome (a clinical duration of 3 to 4 years) with no evidence of cognitive impairment. Despite these remarkable clinical differences among affected members, we found no correlation between the clinical presentation and the codon 129 or codon 219 genotypes. These data suggest that factors as yet unidentified may influence the clinical expression of the disease.