A synthetic peptide containing amino acids 82 to 146 of the human PrP protein (PrP82–146) corresponding to a major PrP fragment isolated from the brains of patients with Gerstmann-Sträussler-Scheinker disease (GSS) [22], was toxic to cultured cortical neurones [23], [24]. This evidence concerns the gene PRNP and Gerstmann-Straussler-Scheinker syndrome.