MAPT and Alzheimer disease: Tauopathies can be classified into several basic groups based on the isoforms that constitute abnormal tau filaments, for example AD, CTE, PiD, and CBD are each characterized by different tau 3MTR- or 4MTR-type molecular folds (Falcon et al., 2018; Carlson and Prusiner, 2021; Vaquer-Alicea et al., 2021).