The extracellular deposition of aggregated amyloid beta (Aβ) plaques and the formation of neurofibrillary tangles of hyperphosphorylated tau protein as well as the suppressed function of the brain cholinergic system are characteristic features of Alzheimer’s disease (AD), but the mechanism of Aβ toxicity is not yet fully understood [247,248]. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.