IDH1 and glioma: The genes encoding IDH1, and to a lesser extent IDH2, were found to be mutated in lower grade gliomas and a subset of glioblastomas that evolved from lower grade tumors, which results in the decreased production of α-ketoglutarate (α-KG) from isocitrate and also the conversion of α-KG to 2-hydroxyglutarate (2-HG) [22].