Given that PSP, PD, and FTD are neuropathologically characterized by degeneration in the midbrain, cerebellum, and (to a lesser extent) neocortical regions1,2,61, our findings may suggest that subtle alterations of CXCR4 and MAPT may predispose to regionally specific brain degeneration in later life. Here, CXCR4 is linked to neurodegenerative disease.