The elevation of haemoglobin by sotatercept is known and was proposed to be via rescue of the inhibition of late‐stage erythropoiesis by GDF11 and activin A.110The contribution of GDF11 to erythropoiesis is not clear as Gdf11 knockout mice were not protected against β‐thalassaemia or myelodysplastic syndromes.111, 112. This evidence concerns the gene GDF11 and myelodysplastic syndrome.