According to the “protein-only” hypothesis formulated in 1980 by Stanley B. Prusiner, which coined the term “prion” (proteinaceous infectious particle) [10], the critical pathological step in prion disorders is the conversion of the normal cellular prion protein (PrPC) into a β-sheet-enriched pathological conformer PrP-scrapie (PrPSc). The gene discussed is PRNP; the disease is scrapie.