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 variants conditions that involve the red blood cells. Elevated Hemoglobin F levels are also associated with Leukemia and myeloproliferative disorders. Hemoglobin H increases the affinity for oxygen. This means that it holds onto the oxygen instead of releasing it into tissue and cells. Hb H usually occurs in some alpha thalassemia and is composed of four beta globin (protein) chains. This variant is usually produced in response to a severe shortage of alpha chains, and usually cause beta chains to function abnormally. Hemoglobin variants Hemoglobin variants are mutant forms of hemoglobin in a population (usually of humans), caused by variations in