Ward and colleagues demonstrate the mutations in isocitrate dehydrogenase 2 (IDH2), commonly found in acute myeloid leukemia (AML), abrogate the enzyme’s wild-type activity and confer to the mutant neomorphic activity that produces the oncometabolite 2-hydroxyglutarate (2-HG) (Figures 2 and 3). This evidence concerns the gene IDH2 and acute myeloid leukemia.