The major pathological hallmarks of AD include brain atrophy, the extracellular deposition of senile plaques composed of insoluble Aβ peptide, and the intracellular formation of neurofibrillary tangles (NFTs) constituted by hyperphosphorylated twisted filaments of the microtubule-associated protein tau in the hippocampus [49,50,51]. The gene discussed is MAPT; the disease is Alzheimer disease.