MAPT and tauopathy: Progressive supranuclear palsy (PSP) is a rare, devastating, relentlessly progressive neurodegenerative movement disorder with a prevalence of ∼6 per 100 000.1-4 Pathologically, PSP is characterized as a ‘tauopathy’ due to the accumulation of the hyperphosphorylated protein tau within the brain, with particularly severe tau aggregation in the basal ganglia, dentate nucleus of the cerebellum and the parietal and frontal lobes.5 PSP is diagnosed primarily on the basis of clinical features, with no currently available biomarkers to aid diagnosis.