-Causes, Symptoms, Diagnosis and Treatment-.
Sickle cell anemia is the most common inherited blood disorder in the United States. Approximately 72,000 Americans have sickle cell anemia, and an additional two million Americans have the sickle cell trait. The disorder primarily affects people of African ancestry, but also occurs in other ethnic groups, including people who are of Mediterranean and Middle Eastern descent. It is characterized by episodes of pain, chronic anemia and severe infections, usually beginning in early childhood. .
The underlying problem stems from the production of an abnormal form of hemoglobin (HbS) produced by those with sickle cell anemia. Red blood cells with normal hemoglobin (HbA) flow easily through the bloodstream, delivering oxygen to all of the cells of the body. Normal red blood cells are soft and flexible, and are shaped like doughnuts. In contrast, HbS molecules tend to clump together, making red blood cells sticky, stiff, and causing them to assume a curved or sickled shape. Unlike normal red cells, the sickled cells cannot squeeze through small blood vessels. Instead, they stack up and cause blockages that deprive the organs and tissue of oxygen-carrying blood. This process produces periodic episodes of pain, and ultimately can damage tissues and vital organs. The stress of springing in and out of sickle shape also damages the cells, causing them to die after ten to twenty days, instead of living out their normal lifespan of 120 days. The premature death of the red blood cells leaves the blood chronically short of red cells, causing a condition called anemia.
The error in the hemoglobin gene results from a genetic mutation that occurred many thousands of years ago in Africa, the Mediterranean basin, the Middle East, and in India. A deadly form of malaria was very common at that time. People who carried a single sickle cell gene had a survival advantage and therefore endured the malaria epidemic at a higher rate than those who had normal hemoglobin genes.