Furthermore, multiple studies have identified increased TLR expression and signaling (particularly TLR2) in the CD34+ cells of patients with myelodysplastic syndromes (MDS), a group of hematopoietic stem cell disorders associated with ineffective hematopoiesis and a high risk of leukemic transformation.11, 12, 13, 14, 15 This fact supports the idea that TLR2 may regulate HSCs, and aberrant signaling through this receptor may have clinically significant effects on HSCs. This evidence concerns the gene CD34 and myelodysplastic syndrome.