Mutant IDH protein produces the oncometabolite D-2-hydroxyglutarate (2HG), which may establish the glioma-CpG island methylator phenotype (G-CIMP) (Noushmehr et al., 2010) by presumably extensive remodeling of the tumor methylome (Turcan et al., 2012). Here, IDH2 is linked to central nervous system cancer.