MAPT and Alzheimer disease: Alzheimer's disease (AD) is pathologically characterized by the presence of extracellular amyloid plaques (APs) and intracellular hyperphosphorylated tau neurofibrillary tangles, which are known to be correlated with cerebrospinal fluid (CSF) levels of amyloid β (Aβ1–42), total tau (t-tau), and phosphorylated tau (p-tau181) [1], [2].