It defines six sequential stages, where tau pathology starts in the pallido-nigro-luysian system and spreads rostrally via the striatum and the amygdala to the cerebral cortex, and caudally to the brainstem and the cerebellum.4 This staging system, which has been replicated and validated,5 was built on post-mortem neuropathological examination of deceased PSP donors, precluding reliable conclusions about the early stages of disease progression. This evidence concerns the gene MAPT and supranuclear palsy, progressive, 1.