While the mixed three-/four-repeat (3R/4R) tau pathology of AD has been shown to be detectable with various tau-specific radiotracers (8–11), detection of 4R tau in progressive supranuclear palsy (PSP) is more challenging and only few examples of detectable binding have been presented so far (12, 13). The gene discussed is MAPT; the disease is Classical progressive supranuclear palsy.