Most recurrent somatic mutations recently evidenced in myeloid malignancies, including myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), and acute myeloid leukemias (AML), affect genes implicated in the regulation of gene expression (RUNX1, TEL/ETV6, TP53, TET2, ASXL1, EZH2, IDH1/2, DNMT3A). The gene discussed is TET2; the disease is myeloproliferative disorder.