Somatic mutation in IDH1 and IDH2 occur respectively in about 6%–16% and 8%–19% of AML patients (11), are frequently associated with normal karyotype and nucleophosmin (NPM1) gene mutations (12), and are without a clear prognostic relevance (13), unless their increased frequency with advanced age (2, 3, 14–16). Here, IDH1 is linked to acute myeloid leukemia.