Given the significant difference in leptin levels in both case and control groups and based on the fact that leptin was much lower in the case group than in the control group as well as its effects on hematopoiesis, the endocrine system and the hypophisis- hypothalamus axis, it can be concluded that low levels of leptin have a role in the development of complications in thalassemia and this association is independent of age and body mass, but it is associated with sex. The gene discussed is LEP; the disease is thalassemia.