FPN critically regulates systemic iron homeostasis, as evidenced by transgenic models: FPN knockout mice exhibit enterocyte/macrophage/hepatocyte iron overload and embryonic lethality [79]; Hepatic FPN specific knockout mice under iron deficiency develop impaired iron mobilization and severe anemia, with red blood cell and hemoglobin levels much lower, demonstrating FPN’s dual role in hepatocyte iron mobilization and macrophage iron recycling during dietary iron stress [112]. The gene discussed is SLC40A1; the disease is Iron deficiency anemia.