Alzheimer’s disease (AD) is characterized by the accumulation in the brain of two types of abnormal structures in the brain, extracellular Aβ amyloid plaques and intraneuronal tau neurofibrillary tangles (Braak and Braak, 1991; Selkoe, 2001). The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.