MAPT and Alzheimer disease: Alzheimer's disease (AD), the most common type of dementia and progressive neurodegenerative disorder worldwide, is characterized by selective neuronal loss, and two histopathological features in postmortem tissue are extracellular amyloid plaques composed of amyloid beta peptide (Aβ) and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein [1].