Isocitrate dehydrogenases IDH1 and IDH2 mutations, which lead to accumulation of 2-hydroxyglutarate in neoplastic cells, are recurrent in AML patients (about 16% of AML patients), particularly in those with normal cytogenetics and NPM1 mutated, and have an unfavorable impact on outcome. The gene discussed is NPM1; the disease is acute myeloid leukemia.