AD is a complex disorder of the central nervous system (CNS) characterized by the pathological formation of extracellular senile plaques in cerebral tissues, which contain aggregates of the amyloid-β peptide (a cleavage product of the amyloid precursor protein), as well as intracellular neurofibrillary tangles derived from the hyperphosphorylated tau protein in affected neurons [98,101]. The gene discussed is MAPT; the disease is Alzheimer disease.