MAPT and early-onset autosomal dominant Alzheimer disease: When the cytosolic tau concentration is elevated, monomeric tau undergoes oligomerization and eventually precipitates into neurofibrillary tangles (NFT) (Greenberg and Davies, 1990; Grundke-Iqbal et al., 1986; Yoshida and Ihara, 1993), which is a hallmark of tauopathies, including Alzheimer’s disease (AD), frontotemporal dementia with Parkinsonism-17 (FTDP-17), and progressive supranuclear palsy (Lee et al., 2011; Ballatore et al., 2007; Spillantini and Goedert, 2013).