TET2 and myelodysplastic syndrome: TET2 is one of the most commonly mutated/deleted genes in adult myeloid malignancies, including ∼30% of cases of myelodysplastic syndrome (MDS), 20% of myeloproliferative neoplasms (MPNs), 17% of de novo acute myeloid leukaemias (AMLs), 30% of secondary AMLs and 50–60% of chronic myelomonocytic leukaemias6, 7, 8, 9.