Tau is a microtubule-associated protein encoded by the MAPT gene, and mutations in MAPT lead to the over-phosphorylation and aggregation of the Tau protein, which in turn leads to the occurrence of neurofibrillary tangles in the CNS, which is the initial pathological manifestation of AD and positively correlates with cognitive impairment. The gene discussed is MAPT; the disease is Alzheimer disease.