In 2016, the WHO updated the diffuse glioma classification by incorporating genetic alterations, especially isocitrate dehydrogenase 1 or 2 (IDH1 or IDH2) hotspot mutations (IDHmut) and 1p19q codeletion, as additional, or even predominant, criteria for tumor classification1, 4. The gene discussed is IDH2; the disease is neoplasm.