Notably, administration of erythropoietin in mice reduced hepcidin levels in a dose-dependent manner, an outcome that has been confirmed in human clinical trials.109 In patients with severe anemia, the hematopoietic system was activated through feedback to upregulate the erythrocyte regulatory factor erythroferrone (ERFE), inhibit the expression of hepcidin, and increase iron absorption. The gene discussed is HAMP; the disease is anemia (phenotype).