PRNP and neurodegenerative disease: As a group, neurodegenerative diseases involving PrP are designated as PrP-prion diseases that can be transmitted experimentally as are the mouse prions used in this study, or iatrogenically, as exemplified by transmission of disease by contaminating CJD-PrPSc in surgical procedures, transplantation, or injection of cadaver-derived human pituitary growth hormone [12, 13].