Sickle Cell Anemia

Sickle cell anemia is an inherited blood disorder characterized primarily by chronic anemia and periodic episodes of pain. In sickle cell anemia, hemoglobin, a component of red blood cells, is defective. Unlike normal red blood cells, which are usually smooth and donut-shaped, sickled red cells cannot squeeze through small blood vessels. Instead, they stack up and cause blockages that deprive organs and tissues of oxygen-carrying blood. This process produces periodic episodes of pain and ultimately can damage tissues and vital organs and lead to other serious medical problems. Normal red blood cells live about 120 days in the bloodstream, but sickled red cells die after about 10 to 20 days. Because they cannot be replaced fast enough, the blood is chronically short of red blood cells, a condition called anemia. Sickle cell anemia is caused by a defect in the hemoglobin beta (HBB) gene and affects millions throughout the world. Direct DNA analysis of the HBB gene is available for prenatal diagnosis when both parents are known or suspected carriers.