CHI3L1 and supranuclear palsy, progressive, 1: NEFM showed the highest average importance, followed by LAMP2, ATP6AP2, CHGB, and CHI3L1 when both 5 and 2 features were used in the classification model (Supplemental Figure S4) These data suggest that the combination of these potential biomarker proteins can be used to marginally improve the classification performance, and NEFM, CHI3L1, and ATP6AP2 are key proteins in differentiating PSP from two other groups, although a further validation experiment is required.