In certain aspects, the present disclosure provides compositions and methods for increasing red blood cell and/or hemoglobin levels in vertebrates, including rodents and primates, and particularly in humans. In some embodiments, the compositions of the disclosure may be used to treat or prevent sideroblastic anemias and myelodysplasia syndromes or one or more complications associated sideroblastic anemias and myelodysplasia syndromes.
