IDH1 and glioblastoma: Considering gliomas overall, the MGMT promoter methylation of IDH-mutant glioma (mainly lower-grade glioma, WHO grade II/III) is significantly higher than that of IDH-wildtype glioma (mainly GBM), and more than 90% of cases of IDH-mutant gliomas have been determined to be MGMT promoter methylated according to the cutoff value used for IDH-wildtype GBM2,23,30.