The IL-6R blocker tocilizumab, which reduces hepcidin generation, increases hemoglobin levels in patients with rheumatoid arthritis81, corrects inflammatory anemia in Castleman disease (associated with excessive IL-6 production)82 and has been trialed as an anti-inflammatory agent in patients with COVID-19 (ref. 83). The gene discussed is IL6R; the disease is Castleman disease.