A comprehensive genomic analysis of glioblastomas has shown that mutations of isocitrate dehydrogenase (IDH) are found in a subset of glioblastoma [1], and subsequent studies have found IDH mutation to be a powerful prognostic factor in malignant gliomas [2], suggesting that IDH mutations represent a clinically distinct subset of gliomas. Here, IDH2 is linked to central nervous system cancer.