PRNP and fatal familial insomnia: Structured around the deviant aggregation of membrane-bound prion protein PrPC found on human gene PRNP, prion diseases are incurable neurodegenerative diseases derived from sporadic (Creutzfeldt–Jakob disease, CJD), genetic (familial CJD, fatal familial insomnia and Gerstmann-Straussler-Scheinker disease) or acquired (kuru and iatrogenic CJD) origin.