Anemia can be a consequence of absolute iron deficiency which is due to chronic blood loss; however, in many patients of chronic diseases, enhanced formation of pro-inflammatory cytokines particularly interleukin 1 (IL-1), interferon gamma (IFN-γ) or tumor necrosis factor alpha (TNF-α) leads to the development of functional IDA and anemia of chronic disease. This evidence concerns the gene TNF and anemia.