Using the anti-PrP monoclonal antibody 1E4 that has an epitope N-terminally adjacent to the 3F4 epitope [37, 38], our recent study identified a novel PK-resistant PrPSc characterized by the presence of dominant PK-sensitive PrPSc in an atypical human prion disease termed variably protease-sensitive prionopathy (VPSPr) [34, 39]. Here, PRNP is linked to prion disease.