MAPT and early-onset autosomal dominant Alzheimer disease: The abnormally phosphorylated form of the microtubule-associated protein tau has been identified as a major component of paired helical filaments in neurofibrillary tangles (NFTs) and plaque neurites in the brains of patients with Alzheimer’s disease.1-3 NFT depositions have been associated with cognitive decline and pathology severity in Alzheimer’s disease,4,5 which are the most prevalent causes of aging-associated dementia.6 Under physiological conditions, tau regulates microtubule stability in the axon, whereas in disease, it is hyperphosphorylated and aggregates.7