The concept of neurotoxic signaling by PrPC has been extended for its binding of other β-sheet-rich oligomers, suggesting a potential central role for PrPC in the pathogenesis of common neurodegenerative “conformational diseases”, such as Parkinson’s disease, Huntington’s disease and, mainly, Alzheimer’s disease (AD) [106,107]. This evidence concerns the gene PRNP and early-onset autosomal dominant Alzheimer disease.