Watanabe et al. [6] dissected multiple biopsies from the same glioma patients and found that there was no case in which IDH mutations had occurred after the acquisition of either a TP53 mutation or 1p/19q codeletion, suggesting that IDH mutations were early events occurring during human gliomagenesis and may affect a common glial precursor cell population. Here, IDH2 is linked to central nervous system cancer.