Prion disease-specific accumulations of PrP (referred to as PrPd) were detected by immunostaining for the abnormal aggregates of PrP characteristically present only in affected tissues [6, 9, 11, 13, 53, 56], complimented with paraffin-embedded tissue (PET) blot analysis of adjacent membrane-bound sections to confirm that these aggregates contained relatively proteinase-K (PK)-resistant prion disease-specific PrPSc [57]. Here, PRNP is linked to prion disease.