Considering the inconsistency of the available data on the number of Treg, their potentially important role in MDS pathogenesis, and functional differences between expressed FOXP3 isoforms, we decided to evaluate not only the number and percentage of Treg in this disease but also the level of FOXP3 isoforms expression in patients with MDS at different stages of the disease. This evidence concerns the gene FOXP3 and myelodysplastic syndrome.