Despite diverse risk factors and clinical presentations, all forms of AD share several common histologic hallmarks, the most prominent being the extracellular amyloid beta (AB) plaques in various brain regions, especially the medial frontal, lateral temporal and parietal cortices, as well as the intraneuronal accumulation of neurofibrillary tangles, composed of hyperphosphorylated tau, a microtubule-associated protein [8]. The gene discussed is MAPT; the disease is Alzheimer disease.