MAPT and Classical progressive supranuclear palsy: Progressive supranuclear palsy (PSP) as one cause of atypical neurodegenerative parkinsonism is now recognized as a range of movement, behavioral, and language syndromes associated with a characteristic 4-repeat tau neuropathology (Boxer et al., 2017), pathologically characterized by tau protein deposition, neuronal loss, and gliosis affecting the brainstem, subcortical, and cortical structures (Litvan et al., 1996; Kovacs et al., 2020).