TET2 (ten-eleven translocation (TET) oncogene family member 2—chromosome 4q24) is a member of the TET family of proteins (TET1–TET3).25TET2 mutations are seen in ~15% of myeloid neoplasms,26 with individual mutational frequencies of; ~60%—CMML, ~15%—MDS, ~15%—polycythemia vera and primary myelofibrosis (PMF), ~20%—secondary AML and ~30%—systemic mastocytosis, with limited prognostic significance.7, 26, 27, 28 TET2 has a dioxygenase enzymatic activity and catalyzes the conversion of 5-methyl-cytosine (5-mc) to 5-hydroxy-methyl-cytosine (5-hmc). Here, TET2 is linked to myelodysplastic syndrome.