Several hematologic malignancies result from mutations in TET2 [4,5], and a reduced level of 5-hmC has frequently been reported in association with TET mutations in myelodysplasia and leukemia [6,7]; furthermore, mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) lead to the production of 2-hydroxyglutarate (2-HG), which inhibits the activity of TET proteins [8,9]. Here, TET2 is linked to hematologic disorder.