MAPT and Alzheimer disease: Alzheimer disease (AD) is a progressive, age-related neurodegenerative disorder characterized by extra- and intracellular accumulation of amyloid β-protein (Aβ), intraneuronal aggregates of hyperphosphorylated forms of the microtubule-associated protein, tau, known as neurofibrillary tangles (NFTs), together with extensive neurodegeneration [1].