Alzheimer’s disease (AD), which is the most common form of dementia in the elderly, is characterized by the presence in the brain of extracellular deposition of amyloid-β (Aβ) in the form of plaques and intracellular accumulation of hyper-phosphorylated Tau (p-Tau) protein as neurofibrillary tangles. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.