IDH1 and oligodendroglial tumor: In 2013, TERT promoter mutations were reported in glioma, and the frequency of these mutations was particularly high among primary glioblastomas (65/78, 83%) and pure oligodendroglial tumors (35/45, 78%), while relatively low in astrocytomas, including grade II astrocytomas, grade III astrocytomas and secondary GBM (4/40, 11%), suggesting that primary GBMs with IDH1/2- wt and TERT promoter mutation could be a heterogenous subtype [23, 24, 26].