In GSS and PrP-CAA, immunoblotting reveals proteinase K (PK)-resistant PrP bands approximately 7–8 kD in size which correlate with the presence of amyloid PrPSc and are distinct from the larger bands usually seen in genetic CJD or FFI [31, 33, 42]. This evidence concerns the gene PRNP and Creutzfeldt Jacob disease.