IDH1 and glioma: Diffuse glioma also shows molecular heterogeneity in the mutational status of isocitrate dehydrogenase 1 and 2 (IDH1/2), the codeletion status of chromosome arms 1p and 19q (1p19q), and the promoter methylation of O(6)-methylguanine-DNA methyltransferase (MGMT) 3.