MAPT and Alzheimer disease: Alzheimer’s disease (AD) is the most common neurodegenerative disorder and is neuropathologically hallmarked by extracellular β-amyloid (Aβ) plaques and by intracellular neurofibrillary tangles consisting of hyperphosphorylated tau protein, which starts 10–20 years before the onset of clinical symptoms (Frisoni et al., 2011; Dubois et al., 2016; Jack et al., 2018).