The value of this in IDH-mutant GBM is less certain, although many studies demonstrate that MGMT promoter methylation is equally important in these tumors [122,123,143,144,145,146,147,148,149], and this beneficial effect of MGMT promoter methylation may in part depend on the presence of TERTp mutation [144,148,149]. The gene discussed is IDH1; the disease is glioblastoma.