On the basis of integrated histomolecular classification scheme, adult diffuse gliomas are currently diagnosed into three main categories: isocitrate dehydrogenase (IDH)-mutant astrocytoma (harboring no 1p19q co-deletion) or oligodendroglioma (harboring 1p19q co-deletion) and IDH-wild-type glioblastoma (GBM) [4, 5]. The gene discussed is IDH1; the disease is oligodendroglioma.