MAPT and fatal familial insomnia: Prion disorders are also referred to as TSEs (transmissible spongiform encephalopathies) and include the bovine spongiform encephalopathy (BSE) in cattle, scrapie in sheep, Creutzfeldt–Jacob diseases (CJD), Gerstman–Sträussler–Scheinker (GSS), fatal familial insomnia (FFI), and kuru in humans [45], which are characterized by a mechanism of protein misfolding adopted also by other neurodegenerative-related proteins, such as Aβ or tau [46].