While the mutation of isocitrate dehydrogenase 1 (IDH1) at the arginine 132 residue (R132) was first identified via the whole-exome sequencing of a cohort of glioblastoma tumors [1], mutations of both IDH1 and IDH2 are now known to be present in a significant percentage of glial neoplasms, particularly lower-grade gliomas [2]. The gene discussed is IDH2; the disease is central nervous system cancer.