Hemoglobin failure, or abnormal hemoglobin (such as that of sickle-cell disease). The ability of each hemoglobin molecule to carry oxygen is normally modified by altered blood pH or CO, causing an altered oxygen–hemoglobin dissociation curve. However, it can also be pathologically altered in, e.g., carbon monoxide poisoning. Decrease of hemoglobin, with or without an absolute decrease of red blood cells, leads to symptoms of anemia. Anemia has many different causes, although iron deficiency and its resultant iron deficiency anemia are the most common causes in the Western world. As absence of iron decreases heme synthesis, red blood cells in iron deficiency
Hemoglobin E gene for β-thalassemia from the other parent. Hemoglobin E/β-thalassemia is a severe disease, and it still has no universal cure. It affects more than a million people in the world. Symptoms of hemoglobin E/β-thalassemia vary but can include growth retardation, enlargement of the spleen (splenomegaly) and liver (hepatomegaly), jaundice, bone abnormalities, and cardiovascular problems. Recommended course of treatment depends on the nature and severity of the symptoms and may involve close monitoring of hemoglobin levels, folic acid supplements, and potentially regular blood transfusions. There is a variety of phenotypes depending on the interaction of HbE and α-thalassemia. The presence of