Abnormal tau hyperphosphorylation leads to the formation of neurofibrillary tangles in several tauopathies, such as AD, progressive supranuclear palsy (PSP), frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), and corticobasal degeneration (CBD). The gene discussed is MAPT; the disease is tauopathy.