IDH1 and oligodendroglioma: Adult diffuse gliomas comprise 3 types: astrocytoma, IDH-mutant; oligodendroglioma, IDH-mutant and 1p/19q-codeleted; and glioblastoma, IDH-wild-type — which includes the genetic modifiers, the mutation status of isocitrate dehydrogenase (IDH) genes, and codeletion of chromosome arms 1p and 19q (1p/19q codeletion) (2, 9, 10).