IDH1 and oligodendroglioma: There were 31 patients in the study with age at the time of surgery ranging from 22 to 83 years: 18 patients (58%) had glioblastoma WHO grade IV, 2 of which were IDH-mutant; 10 patients (32%) had IDH-mutant and 1p/19q-codeleted oligodendroglioma; and 3 patients had IDH-mutant anaplastic astrocytomas (Table 1).