IDH1 and oligodendroglioma: Verified pathology in the 40 patients included: 26 GBMs, isocitrate dehydrogenase (IDH) wild type; seven astrocytomas, IDH mutant, alpha thalassemia/mental retardation syndrome X-linked lost; four oligodendrogliomas, IDH mutant, 1p/19q-codeleted; two meningiomas (WHO grade 1); and one metastatic tumor (adenocarcinoma).