Many studies have been carried out to investigate the relationship between structural features and neurotoxicity of amyloid proteins involved in diseases, such as β-Amyloid (βA) in Alzheimer’s disease (AD), α-Synuclein (αS) in Parkinson’s disease (PD), prion protein in spongiform encephalopaties, inslet amyloid polypeptide in type II diabetes. This evidence concerns the gene PRNP and Alzheimer disease.