MAPT and Alzheimer disease: In order to investigate the specificity of the tau SAA for AD as compared to other tauopathies and synucleinopathies, brain homogenates from 15 cases of AD, 3 cases of PSP, 3 cases of PD, 3 cases of MSA and 18 control cases were analyzed (cohort 1, Table 1 and Additional file 1: Table S2).