Iron deficiency may be involved in hypoxic pulmonary hypertensive vascular injury by upregulating pulmonary artery endothelial cell levels and promoting apoptosis of endothelial cells and proliferation of lung artery smooth muscle cells, and further upregulation of hepcidin levels leads to a vicious cycle of iron deficiency.[35] It is believed that serum iron concentration affects pulmonary function. The gene discussed is HAMP; the disease is nutritional disorder.