MAPT and Alzheimer disease: Alzheimer’s disease (AD) is characterized by the formation of two types of protein aggregates in the brain: neurofibrillary tangles (NFTs) in neurons formed by hyperphosphorylated tau and extracellular β-amyloid plaques formed by the accumulation of secreted Aβ (Suh and Checler, 2002; Small and Gandy, 2006).