PRNP and Alzheimer disease: The proteins incriminated in the accumulation of cerebral misfolded aggregates include amyloid β (Aβ) in AD; tau in AD and FTD; α- synuclein (α- Syn) in PD; prion proteins (PrPs) in PrDs and TAR DNA-binding protein 43 (TDP-43) in ALS [5–9].