Abstract: The invention features methods of treating iron overload in a subject by administering BMP or hepcidin inhibitors, such as ALK2 inhibitors. The invention also features methods of decreasing iron levels in a subject by administering BMP or hepcidin inhibitors.

Abstract: The invention features methods of treating or preventing the development of a cardiovascular-related disease by administering to the subject a BMP inhibitor or a hepcidin inhibitor, such as an ALK2 inhibitor.

Abstract: The invention features methods of treating or preventing lymphopenia in a subject treated with a BMP inhibitor or a hepcidin inhibitor, such as an ALK2 inhibitor, by co-administering an iron supplement with the inhibitor, and methods of treating a subject who has or is at risk of developing a disease or condition that can be treated with a BMP inhibitor or a hepcidin inhibitor, such as an ALK2 inhibitor, by administering to the subject a BMP inhibitor or a hepcidin inhibitor and an iron supplement.

Abstract: The invention features polypeptides that include an extracellular ActRII variant, such as an ActRIIA variant, ActRIIB variant, or ActRII chimera. In some embodiments, a polypeptide of the invention includes an extracellular ActRII variant fused to an Fc domain monomer or moiety. The invention also features pharmaceutical compositions containing said polypeptides and methods of using the polypeptides to treat diseases and conditions that can be treated with erythropoietin or an erythropoiesis-stimulating agent.