As described above, IDH mutation and the resulting production of the oncometabolite 2-HG results in a global hypermethylated state in IDH-mutant astrocytomas, which can be detected with DNA methylation profiling and can be used to discriminate these tumors from other histologically similar neoplasms, including oligodendroglioma and glioblastoma [33]. The gene discussed is IDH2; the disease is oligodendroglioma.