Conflicting observations were reported regarding the effect of DAC on Treg numbers in vivo in humans; Costantini et al. [26] and Bontkes et al. [36] reported that 9 months (68 patients) or 3 months (9 patients) of DAC treatment of MDS patients did not result in an increase of FOXP3-expressing cells, while Stübig et al. [23] and Schroeder et al. [25] found increased Treg numbers in AML, CMML, and MDS patients. The gene discussed is FOXP3; the disease is chronic myelomonocytic leukemia.