Genetic prion diseases, such as familial Creutzfeldt-Jakob disease (fCJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), and fatal familial insomnia (FFI), are caused by a sort of mutations within human PrP encoding PRNP gene. The gene discussed is PRNP; the disease is Gerstmann-Straussler-Scheinker syndrome.