MAPT and Alzheimer disease: Abnormal phosphorylation of tau is a pathological hallmark of AD and other tauopathies, which is known to trigger tau pathology by reducing its affinity to microtubules, enhancing aggregation, altering its interactions with other proteins, and missorting it from axons to the somatodendritic compartments in neurons (Wang and Mandelkow, 2016).