Loss of H19 imprinting has been described in adult T-cell leukaemia/lymphoma (ATL) [157] and decreased H19 expression was found in the bone marrow of patients with clinically untreated chronic myeloproliferative disorders, including chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) and chronic myelomonocytic leukaemia (CMML) [205,206] and AML [207]. The gene discussed is H19; the disease is acquired polycythemia vera.