AD is characterized by neurofibrillary tangles (NFTs), intracellular aggregates of hyperphosphorylated tau protein (p-tau) within neuronal cells, and senile plaques (SPs), which result from the extracellular deposition of the β-amyloid (Aβ) peptide derived from the processing of amyloid precursor protein (APP). The gene discussed is MAPT; the disease is Alzheimer disease.