MAPT and Alzheimer disease: AD is characterized by the extracellular deposition of aggregates of β-amyloid (Aβ) (Yoshida and Ihara, 1993) forming senile plaques, in addition to the intraneuronal accumulation of hyperphosphorylated tau protein as neurofibrillary tangles (Selkoe, 2004; Braak et al., 2006; Hardy, 2006).