IDH2 and glioma: 3-Hydroxyglutaric acid (OH-GlutAcid) was significantly increased in the CSF of patients with IDH-mutated glioma, whereas the other 17 metabolites, especially p-cresol sulfate (p-cresol-SO4), homocysteine (HCys), glycolithocholic acid sulfate (GLCAS), hexoses (H1), and ceramide (d18:1/18:0), were decreased.