Prion diseases are a spectrum of transmissible lethal neurodegenerative diseases characterized by cognitive impairment, motor dysfunction, spongiosis, astrogliosis and cerebral deposition of insoluble PRNP (prion protein).110, 111 In prion diseases, the native form of prion protein PRNPC is converted into PRNPSC, a pathogenic form that is protease-resistant and prone to aggregation.112. This evidence concerns the gene PRNP and Cognitive impairment.