MAPT and progressive supranuclear palsy: Progressive supranuclear palsy (PSP) is a neurodegenerative disease and common cause of atypical parkinsonism, with an estimated prevalence of 5 to 7 per 100,000.1 The neuropathology of PSP, the gold standard for diagnosis, is centred on the structural microtubule‐associated protein tau, encoded by the MAPT gene.2