MAPT and Alzheimer disease: Two neuropathological hallmarks of AD are the extracellular senile plaques mainly composed of amyloid-β (Aβ) peptide and intracellular neurofibrillary tangles formed by hyperphosphorylated tau protein (Castellani et al., 2010; Ballard et al., 2011; Mandelkow and Mandelkow, 2012).