Studies over the past two decades have clarified several genetic alterations in gliomas, such as mutations in IDH1/2, TP53 and ATRX, TERT promoter mutation, MGMT promoter methylation and 1p/19q co-deletion, etc. Some of them contribute to glioma classification, prognosis or guidance in therapeutic decisions. The gene discussed is MGMT; the disease is central nervous system cancer.