PRNP and Alzheimer disease: Western blot of Tau aggregates from PrP-CAA (Q160X), GSS (F198S), and AD show identical pattern of migration and immunoreactivity using antibodies against 3R- and 4R-au, strongly suggesting that Tau aggregates in PrP-CAA (Q160X) and GSS (F198S) are composed by 3R- and 4R-au isoforms.