MAPT and early-onset autosomal dominant Alzheimer disease: Neuropathological Tau accumulation occurs in neurodegenerative disorders of Alzheimer's disease (AD)1, frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), progressive supranuclear palsy, chronic traumatic encephalopathy (CTE), and related diseases, commonly known as tauopathies (1, , –4).