IDH1 R132 mutations are gain-of-function, causing the enzyme to produce 2-hydroxyglutarate (2-HG) [7, 27] and IDH1-mutant tumors display distinct DNA methylation profiles with global hypermethylation, termed a glioma-CpG island methylator phenotype (G-CIMP) [26, 35, 38]. The gene discussed is IDH1; the disease is glioma.