AD is pathologically defined by the presence of amyloid plaques, hyperphosphorylated tau proteins, and neurofibrillary tangles; however, oxidative–nitrative stress, endoplasmic reticulum stress, mitochondrial dysfunction, inflammatory cytokines, pro-apoptotic proteins, and altered neurotransmitter levels are all common etiological attributes in its pathogenesis. The gene discussed is MAPT; the disease is Alzheimer disease.