DNMT1 and myelodysplastic syndrome: In addition, with the support by the role of DNMT1 in MDS and myeloid leukemia as reported in a previous review (40) and reports indicating a reduction in mRNA level of DNMTs by HDZ (37) and an abnormally high expression level of DNMTs in cell lines of MDS and myeloid leukemia including AML and CML (41), we suggest that HDZ alone may have enough efficacy to inhibit MDS or myeloid leukemia while previous trials selected a combination of HDZ and VAL (23, 24, 27, 28).