Samples from 38 IDH-wild-type GBM (GBM01–38), 1 IDH-mutated GBM (GBMm01), and 1 gliosarcoma (GS01) patient and the commercial GBM cell line T98G were subjected to DNA methylation analysis of the MGMT promoter and 4 enhancers by HRM analysis and PSQ. The gene discussed is IDH1; the disease is gliosarcoma.