MAPT and Alzheimer disease: AD is characterized by abnormal accumulation of misfolded extracellular amyloid‐β (Aβ) and intracellular neurofibrillary tangles (NFTs) of tau proteins, which are associated with synaptic disruption and subsequent neuronal death (Braak & Braak, 1991; Terry et al., 1991; Wenk, 2003).