O6-methylguanine-DNA methyltransferase (MGMT) is a DNA-repair protein that protects glioblastoma tumor cells against alkylating agents including TMZ by removing alkyl adducts from the O6-position of guanine.[1] The landmark European Organization for Research on Treatment Cancer (EORTC) 26981 trial [5]–[6], along with a series of confirmatory studies [7]–[10], had demonstrated that epigenetic silencing of MGMT gene by promoter methylation was of predictive significance for prolonged survival to the combination of TMZ and RT in younger glioblastoma patients (<70 years). The gene discussed is XRCC6P5; the disease is glioblastoma.