During the 2007 NFL Season, Pittsburgh Steelers safety Ryan Clark became ill during a game against the Denver Broncos in Mile High Stadium. He was rushed to the hospital and stabilized before returning to Pittsburgh. Once home, his spleen and gall bladder were removed in separate operations. What was the cause of this professional athlete’s extremely serious condition? Sickle cell anemia.
Sickle cell anemia (sickle cell disease) is a disorder of the blood caused by an inherited abnormal hemoglobin (an oxygen-carrying protein within the red blood cells). The abnormal hemoglobin causes distorted (sickled) red blood cells. The sickled red blood cells are fragile and prone to rupture. When the number of red blood cells decreases from rupture (hemolysis), anemia is the result. This condition is referred to as sickle cell anemia. The irregular sickled cells can also block blood vessels causing tissue and organ damage and pain.
Sickle cell anemia is one of the most common inherited blood anemias. The disease primarily affects Africans and African Americans. It is estimated that in the United States, some 50,000 African Americans are afflicted with the most severe form of sickle cell anemia. Overall, current estimates are that one in 1,875 U.S. African American is affected with sickle cell anemia.
How is sickle cell anemia diagnosed?
Sickle cell anemia is suggested when the abnormal sickle-shaped cells in the blood are identified under a microscope. Testing is typically performed on a smear of blood using a special low-oxygen preparation. This is referred to as a sickle prep. Other prep tests can also be used to detect the abnormal hemoglobin S, including solubility tests performed on tubes of blood solutions. The disease can be confirmed by specifically quantifying the types of hemoglobin present using a hemoglobin electrophoresis test.
Prenatal diagnosis (before birth) of sickle cell anemia is possible using amniocentesis or chorionic villus sampling. The sample obtained is then tested for DNA analysis of the fetal cells.
The major features of sickle cell anemia include:
- Fatigue and Anemia
- Pain Crises
- Dactylitis (swelling and inflammation of the hands and/or feet) and Arthritis
- Bacterial Infections
- Splenic Sequestration (sudden pooling of blood in the spleen) and Liver Congestion
- Lung and Heart Injury
- Leg Ulcers
- Aseptic Necrosis and Bone Infarcts (death of portions of bone)
- Eye Damage
The treatment of sickle cell anemia is designed according to which of the individual features of the illness are present. In general treatment is directed at the management and prevention of the acute manifestations as well as therapies directed toward blocking the red blood cells from stacking together. There is no single remedy to reverse the anemia. It is, therefore, important that family members have an optimal understanding of the illness and that communication with the doctors and medical personnel be maintained.
What is the outlook (prognosis) for patients with sickle cell anemia?
The life expectancy of persons with sickle cell anemia is reduced. Some patients, however, can remain without symptoms for years, while others do not survive infancy or early childhood. Nevertheless, with optimal management patients can now survive beyond the fourth decade.
Most patients suffer intermittent pain crises, fatigue, bacterial infections, and progressive tissue and organ damage. Impaired growth and development is the end result of the physical and emotional trauma that is endured by children with sickle cell anemia.
Causes of death include bacterial infection (the most common cause), stroke or bleeding into the brain, and kidney, heart, or liver failure. The risk of bacterial infections does diminish after three years of age. Nevertheless, bacterial infections are the most common cause of death at any age. Therefore, any signs of infection in a person with sickle cell anemia must be reviewed with a doctor to prevent damage and save lives.
Interestingly, the sickle cell gene somewhat protects against malaria infection. This makes those with sickle cell trait (gene carriers) at least partially resistant to malaria. Furthermore, the geographic distribution of the sickle cell gene is similar to that of malaria infection. Sickle cell anemia is a lethal condition that threatens life. But there may be a selective advantage to being a sickle cell carrier (trait) if the person resides in an area of the world where malaria is very common. The advantage a person with sickle cell trait has over a non-carrier of the gene may explain why sickle cell anemia did not disappear from the world even though it is lethal.
The sickle cell gene is not a “black gene.” It just happens to disproportionately occur in the black population. When a black person who carries a sickle cell gene has children with a non-black person, the children may inherit the sickle cell gene regardless of their color. There are also non-black persons who carry the sickle cell gene.
