The plasma level of complement C4a des Arg was measured in both control and patient groups: 5.8 ± 3.1 μg/mL (the control group, n = 19) and 6.4 ± 9.6 μg/mL (the RCMD group, n = 19). This evidence concerns the gene C4A and myelodysplastic syndrome with multilineage dysplasia.