3R/4R tau seeding activity was detectable in all cases (p < 0.0001 when compared to the tau KO mouse BH negative control), being on average 100-1000-fold higher in cases with a primary AD diagnosis compared to controls, 4R tauopathies, and synucleinopathies (Fig. 1c, Supplementary Fig. 1, online resource), consistent with our prior observations [31, 43]. Here, MAPT is linked to Alzheimer disease.