IDH2 and glioma: The IDH mutation, which is present in about 80% of so-called “low-grade” (WHO grade II) gliomas and secondary glioblastomas, plays an important role in tumorigenesis [3] and results in a loss of enzyme function, production of 2-hydroxyglutarate (2-HG), and likely consequent DNA cytosine-hypermethylation [4].