Abstract: The invention features polypeptides that include an extracellular ActRIIA variant. In some embodiments, a polypeptide of the invention includes an extracellular ActRIIA 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 including neuromuscular diseases, osteogenesis imperfecta, myelofibrosis, thrombocytopenia, neutropenia, and age-related and treatment-related metabolic disease.

Abstract: The invention features polypeptides that include an extracellular ActRIIB variant. In some embodiments, a polypeptide of the invention includes an extracellular ActRIIB 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 including neuromuscular diseases, osteogenesis imperfecta, myelofibrosis, thrombocytopenia, neutropenia, and metabolic disease.

Abstract: The invention features polypeptides that include an extracellular ActRII chimera. In some embodiments, a polypeptide of the invention includes an extracellular ActRII chimera fused to an Fc domain monomer or moiety. The invention also features pharmaceutical compositions and methods of using the polypeptides to treat diseases and conditions involving weakness and atrophy of muscles, bone damage, low red blood cell levels (e.g., anemia or blood loss), low platelet levels (e.g., thrombocytopenia), low neutrophil levels (e.g., neutropenia), fibrosis, metabolic disorders, and/or pulmonary hypertension.

Abstract: The invention relates to methods of treating multiple osteochondroma and anemia resulting from iron imbalance using small molecule ALK2 inhibitors.