In the last 3 years, alone mutations in the genes TET2, IDH1, IDH2, DNMT3a, and EZH2 have all been found in patients with myeloproliferative neoplasms (MPNs), myelodysplastic syndromes (MDSs), and/or acute myeloid leukemia (AML). The gene discussed is IDH1; the disease is myelodysplastic syndrome.