MAPT and early-onset autosomal dominant Alzheimer disease: Alzheimer’s disease (AD) is the most common cause of dementia with key neuropathological features that include senile plaques comprised of amyloid β (Aβ) peptides and intracellular aggregates of the soluble microtubule-associated protein tau, which misfolds into insoluble, filamentous and hyperphosphorylated inclusions (neurofibrillary tangles or NFTs)1.