Using 18F-PI-2620 PET for tau imaging in clinically diagnosed CBS (n = 24) and PSP-RS patients (n = 22), we tested if (i) functionally connected brain regions show correlated 18F-PI-2620 PET levels and whether (ii) brain-wide tau-PET uptake patterns are associated with the functional connectivity pattern of subcortical epicenters with highest tau pathology. The gene discussed is MAPT; the disease is X-linked retinoschisis.