PRNP and Gerstmann-Straussler-Scheinker syndrome: Gerstmann-Sträussler-Scheinker syndrome (GSS) is an autosomal dominant neurodegenerative disease caused by point mutations in the prion protein gene (PRNP)<i>.</i> While variable, the clinical presentation typically encompasses progressive cerebellar ataxia, pyramidal signs, and cognitive impairment.