Low plasma sEV 3R/4R tau ratios (<0.77) discriminated clinical PSP cases form all other individuals in subcohort 2 (sensitivity: 93.25%, CI [88.25–96.58%]; specificity: 95.25%, CI [92.68–97.12%]) as well as PSP/GGT-type tau pathology cases from other pathology-confirmed cases (sensitivity: 100%, CI [39.76–100%]; specificity: 100%, CI [93.94–100%]). The gene discussed is MAPT; the disease is supranuclear palsy, progressive, 1.