This significant reduction in the RBC count and hemoglobin (Hb) concentration in the arthritis-induced rats could be attributed to two reasons: the first may be due to the premature destruction of red blood cells, and the second cause may be due to abnormal storage of iron in the reticuloendothelial system and synovial tissue, which might have caused low bone marrow iron availability due to decreased iron release by the mononuclear phagocyte system activation which had probably have resulted in ineffective erythropoiesis causing anemia. The gene discussed is GSTM1; the disease is anemia (phenotype).