PRNP and Creutzfeldt Jacob disease: Four subtypes of the prion disease Creutzfeldt-Jakob disease (CJD) have been described to date including familial CJD (fCJD), linked to germline mutations of the prion protein (PrP) gene [1], and iatrogenic CJD (iCJD), a transmissible form of the disease in which the disease form of prion protein (PrPsc) is acquired from growth hormone, dura mater grafts, or corneal transplantation [2].