The depositions of amyloid β protein (Aβ) in the extracellular neuritic plaques, neurofibrillary tangles containing hyperphosphorylated tau protein in the neurons of the hippocampus and other parts of the cortex resulting in brain atrophy, are the most important neuropathological features associated with Alzheimer's disease (AD) [1–3]. The gene discussed is MAPT; the disease is Alzheimer disease.