PRNP and Alzheimer disease: These proteins are alpha-synuclein and parkin in PD [5,6], huntingtin in HD [7], presenilin1 and presenilin-binding proteins in AD [8], polyglutamine-containing proteins in polyglutamine diseases [9], superoxide dismutase in ALS [10], the prion protein (PrP) in prion diseases [11,12], cystic fibrosis transmembrane conductance regulator in cystic fibrosis [13].