PRNP and scrapie: Conformational conversion of the normal cellular isoform of prion protein, designated PrPC, to the abnormally folded, amyloidogenic isoform, PrPSc, is a key pathogenic event in prion diseases, a group of fatal neurodegenerative disorders that include Creutzfeldt–Jakob disease (CJD) in humans, scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle, and chronic wasting disease in deer [1,2,3,4].