MAPT and Alzheimer disease: The underlying biology of AD includes aggregation of soluble amyloid species into insoluble amyloid plaques, hyperphosphorylation of tau with formation of intracellular neurofibrillary tangles, and neuronal death along with a variety of related processes including neuroinflammation, synaptic and circuit dysfunction, mitochondrial and bioenergetic disorders, epigenetic changes, and vascular abnormalities [1, 2].