MAPT and Alzheimer disease: As a progressive neurodegenerative disease with complex pathobiology, AD is characterized clinically by progressive cognitive impairment and pathologically by extracellular accumulation of amyloid-beta (Aβ) plaques, intracellular neurofibrillary tangles (NFTs) composed of highly phosphorylated tau proteins, and loss of neurons and synapses [1,3].