PRNP and prion disease: Transmissible spongiform encephalopathies (TSEs) or prion diseases are invariably fatal neurodegenerative diseases characterized by the conversion of the cellular prion protein (PrPC: classical PrPC) to the partially protease-resistant form (PrPSc: classical PrPSc, which is the hallmark of prion diseases) and its deposition in the central nervous system [1, 2].