Although homozygous double-mutant AML genetic mouse models of Tet2–/– Flt3ITD/ITD (1, 5) and Dnmt3afl/fl Cre Flt3ITD/ITD (2) have been shown to promote leukemogenesis, heterozygosity of these mutations and their role in driving leukemogenesis in a head-to-head manner has never been examined, to our knowledge. This evidence concerns the gene TET2 and acute myeloid leukemia.