MAPT and early-onset autosomal dominant Alzheimer disease: Tau is a natively unstructured protein with little intrinsic tendency to aggregate in vitro, yet a class of neurodegenerative disorders called tauopathies, including Alzheimer’s disease (AD), progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), argyrophilic grain disease (AGD), Pick's disease (PiD), and frontotemporal dementia (FTD) [1], is characterized by aggregation of aberrantly post-translationally modified tau in the brain.