MAPT and Alzheimer disease: Paired helical filaments and the hyperphosphorylation of tau are two of the most recognized molecular characteristics in Alzheimer's disease (AD) and several other neurodegenerative tauopathies, for example, frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) and progressive supranuclear palsy (PSP) [28].