Alzheimer’s disease (AD) is a complex neurodegenerative disorder characterized by multiple pathological features, including extracellular amyloid-beta (Aβ) plaques, neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein, neuroinflammation, synaptic dysfunction, neuronal loss, glial activation, and impaired neurogenesis. The gene discussed is MAPT; the disease is Alzheimer disease.