IDH mutations were found in only 25 out of 52 cases (48.1%), this was probably due to: the inclusion of primary glioblastoma and glioblastoma with oligodendroglioma component, failure to detect rare IDH1 and IDH2 mutations by DNA sequencing, and/or selection bias due to the preoperative availability of MRS. The gene discussed is IDH2; the disease is oligodendroglioma.