MAPT and Alzheimer disease: Within AD, tau is pathologically hyperphosphorylated leading to dissociation from microtubules, which then forms aggregates termed neurofibrillary tangles, with this hallmark detectable in the brain 2–5 years prior to symptomatic onset (Alzheimer Association, 1911; Bejanin et al., 2017; Vogel et al., 2020).