Ten-Eleven Translocation Methylcytosine Dioxygenase 2 (TET2)

TET2 gene in bone marrow cells from 320 patients with myeloid cancers and identified TET2 defects in 15 (19%) of 81 patients with myelodysplastic syndromes, 24 (12%) of patients with myeloproliferative disorders, 5 (24%) of patients with secondary AML, and 2 (22%) of 9 patients with chronic myelomonocytic leukemia. The TET2 defects were present in hematopoietic stem cells and preceded the JAK2 V617F mutation in the 5 patients that were studied. In these individuals, TET2 mutations were found in most of their bone marrow cells and in various lineages of differentiation, including CD34+ progenitor cells, suggesting that TET2 mutations occur early during disease evolution. TET2 expression was shown to be elevated in hematopoietic cells with highest expression in granulocytes, consistent with a function in myelopoiesis.