Furthermore, IDH-mutations invariably present with additional molecular alterations which again are prognostically important: IDH-mutations co-occur either with mutations in TP53 and ATRX associating with a less-favorable prognosis or with whole-arm 1p/19q codeletion and TERT promoter (TERTp) mutations associating with the most favorable prognosis for IDH-mutant gliomas [9–11]. The gene discussed is IDH2; the disease is central nervous system cancer.