IDH2 and glioma: As patients with IDH1 mutation have a greater 5 year survival rate than patients with wild-type IDH1 gliomas (93% vs 51%) when correcting for age,31 2HG is also an important prognostic marker.18 As opposed to what happens in patients affected by hydroxyglutaric aciduria metabolic disorders, in patients with IDH-mutant gliomas, 2HG levels increase in tumor tissue but not in blood levels.