Alzheimer’s disease (AD), an age-dependent neurodegenerative disorder with progressive cognitive impairments, is characterized by the accumulation of the extracellular β-amyloid peptide (Aβ) within the brain along with hyperphosphorylated and cleaved forms of the microtubule-associated protein, Tau, as the pathological hallmarks. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.