MAPT and Alzheimer disease: We classified tau pathology-related PTMs in three categories namely (1) 4R-specific (PTMs mostly observed in tauopathies with 4R-tau aggregates; Table 2), (2) 3R-specific (PTMs mostly observed in tauopathies with 3R-tau aggregates; Table 2) and (3) AD-specific (PTMs exclusively observed in AD; Table 2).