PRNP and Creutzfeldt Jacob disease: Familial/genetic CJD (fCJD/gCJD) accounts for about 10–15% of CJD cases worldwide2,3, which closely links to various pathogenic mutations in the prion protein-encoding gene, PRNP. Up to now, about 50 different pathogenic mutations in PRNP have been addressed, which result in dominant hereditary prion diseases4,5.