MAPT and Alzheimer disease: Tau is a microtubule-associated protein that functions to stabilize axonal microtubules and to transport mitochondria along axons, and taupathies (including tau hyperphosphorylation) are a characteristic feature of several neurodegenerative diseases including AD, progressive supranuclear palsy, corticobasal degeneration, and Pick’s disease (Ittner and Götz 2011; Khanna et al. 2016).