MAPT and supranuclear palsy, progressive, 1: Neuropathologically, PSP is defined by neuronal loss in the basal ganglia and brainstem with widespread occurrence of neurofibrillary tangles (NFTs; Williams and Lees, 2009; Yoshida et al., 2022) and accumulation of phosphorylated tau (p-tau) protein in the brain (Williams and Lees, 2009).