Gerstmann–Sträussler–Scheinker disease with P102L–V129 mutation: a case with psychiatric manifestations at onset

Gerstmann–Sträussler–Scheinker disease (GSS) is an adult onset, rare, genetically determined autosomal dominant prion disease. Clinically, it is characterized predominantly by slowly progressive spino-cerebellar dysfunction with ataxia, absent reflexes in the legs and cognitive impairment. Onset is usually in the fifth decade and in the early phase, ataxia is predominant. Mutations in the prion protein gene (PRNP) had been identified and the most important of these is at codon 129. A genotype–phenotype relationship with genetic polymorphism at residue 129 between methionine and valine has been supposed. We describe a patient with GSS and P102L–V129 mutation in which the onset with prominent psychiatric features characterized by apathy and depression and not with cerebellar sign and the clinical course with seizures, nor observed in P102L–V129 cases, allow us to confirm observations that the GSS caused by the 102 mutation is influenced by the codon 129 polymorphism with a specific genotype–phenotype influence, but probably other additional factors might be considered as background for phenotypic variability.