Alzheimer’s disease, the most prevalent form of dementia worldwide, particularly in middle-aged and elderly populations, is a progressive neurodegenerative disorder characterized by two primary pathophysiological hallmarks: Positive lesions include the accumulation of amyloid-β plaques, tau-associated neurofibrillary tangles, dystrophic neurites, neuropil threads, and other abnormal protein aggregates. The gene discussed is MAPT; the disease is Alzheimer disease.