Red blood cells contain the protein hemoglobin, which binds to the oxygen that is delivered to tissues throughout the body. In sickle cell disease, the red blood cells contain abnormal types of hemoglobin, which cause the red blood cells to become misshapen. Approximately 72,000 Americans suffer from some form of sickle cell disease, according to the University of Maryland Medical Center. Merck Manuals adds that African-Americans are the chiefly affected segment of the population. There are several different types of sickle cell disease, which differ based on hemoglobin type.
Sickle Cell Anemia
Sickle cell anemia is the most severe type of sickle cell disease. A person with sickle cell anemia has two hemoglobin S genes, which results in the development of red blood cells that carry exclusively hemoglobin S. The "S" in hemoglobin S stands for "sickle." The Sickle Cell Disease Association of America reports that red blood cells with hemoglobin S circulate in the blood stream for only for 16 days before dying, compared to the 120 days for normal red blood cells. The body cannot supply enough red blood cells to replace all the ones that die, resulting in anemia. Furthermore, hemoglobin S causes the red blood cells to distort into an abnormal "C" shape, similar to the shape of a sickle. The shape of these cells causes them to get caught in small blood vessels, and can cause a blockage that restricts blood flow. The blockages prevent tissue from receiving the appropriate amount of oxygen, and the possible result is severe pain and tissue damage.
Sickle Cell-Hemoglobin C Disease
People with sickle cell-hemoglobin C disease have two different hemoglobin genes: one hemoglobin S gene, and one hemoglobin C gene, according to the University of Maryland Medical Center. These two abnormal genes result in red blood cells that have two abnormal types of hemoglobin, though hemoglobin S causes more severe anemia than hemoglobin C. However, because only half the hemoglobin is hemoglobin S, and half is of the less deformed C-type, affected persons have a milder form of anemia than people with sickle cell anemia.
Sickle Beta Thalassemia
Sickle beta-plus thalassemia involves the inheritance of two different types of genes: one codes for the red blood cell sickle-shape, causing hemoglobin S, and the other codes for beta thalassemia, which is another type of anemia. There are two types of beta thalassemia: zero and plus, according to the Centers for Disease Control and Prevention. Beta-zero thalassemia causes a more severe form of anemia than beta-plus thalassemia. Thus, people with sickle beta-zero thalassemia have more severe anemia than people with sickle beta-plus thalassemia.
