Although different mechanisms may affect 5-hmC reduction in cancer, the mutation of Ten-Eleven Translocation Enzyme-2 (TET2) is responsible for the reduction of 5-hmC levels in T-Cell Lymphoma and myeloproliferative tumors.8, 9, 22 The reduction of 5-hmC levels in CD4+ lymphoproliferative diseases may be an indicator of TET2 mutations. The gene discussed is TET2; the disease is cancer.