Severe COVID-19 is characterized by a cytokine-driven acute-phase response in which IL-6–mediated induction of hepcidin redistributes iron into storage compartments, producing hypoferremia with concurrent hyperferritinemia; multiple clinical cohorts report that elevated hepcidin and ferritin strongly correlate with disease severity and mortality [200,201]. The gene discussed is HAMP; the disease is COVID-19.