In humans four different mutations encoding PrP with a C-terminal truncation and lacking the GPI anchor (Y145X, Q160X, Y163X, and Y226X) have been discovered in patients with fatal neurodegenerative disease associated with perivascular amyloid PrPres deposition and CAA neuropathology similar to that seen in scrapie-infected tg44 mice[22-25]. Here, PRNP is linked to scrapie.