Sporadic CJD is not a uniform disorder in terms of its clinical and neuropathological phenotypes and is subclassified according to the polymorphism at codon 129 of the PRNP sequence (Methionine/Valine) and to the electromobility of the PK resistant core of the abnormal PrP (PrPres: either as type 1 or 2) [45]. Here, PRNP is linked to Creutzfeldt Jacob disease.