The lack of PrP-CTF12/13 or fPrP11-12 in vCJD and most iCJD including p-dCJD may be associated with a prion formation pathway that is different from a pathway present in other types of prion diseases that have no plaque deposition but accompany with the small fragments. This evidence concerns the gene PRNP and variant Creutzfeldt-Jakob disease.