Sickle Cell Disease

(Hemoglobin S; Sickle Cell Anemia)

Sickle cell disease is the general term for a group of inherited blood disorders characterized by abnormal hemoglobin, the pigment in red blood cells that contains iron and carries oxygen throughout the body. Sickle cell disorders derive their name from the abnormal crescent shape of the red blood cells, which are also easily destroyed.

The disease varies greatly in severity, but it invariably causes anemia. Thus, fatigue, shortness of breath, delayed growth, and rapid heartbeat -- common components of anemia -- generally occur. The anemia, however, is not the most serious aspect of the disorder. From time to time, a person with sickle cell disease develops an aplastic crisis in which the circulation is flooded with sickled cells that clog small blood vessels and may block blood flow to vital organs. In time, the kidneys, lungs, heart, and joints may suffer permanent damage. In severe cases, early death from kidney failure, respiratory failure, or stroke is common.

Sickle cell disease occurs in most racial and ethnic groups, but is most widespread among people of African origin. In the United States, it affects about 150 in every 100,000 African-Americans, or a total of 60,000 to 80,000 people. To develop sickle cell disease, a child normally must inherit the gene from both parents. Those who inherit only one gene become carriers of the sickle cell trait and can pass the gene to the next generation.

Although a person with the sickle cell trait may have deformed blood cells, he usually has no symptoms. However, travel to a high altitude may actually precipitate symptoms because reduced availability of oxygen can accelerate breakdown of the fragile red blood cells.

A rare type of sickle cell disease, called hemoglobin S-C, develops when a child inherits the sickle cell trail from one parent and a variant called hemoglobin C from the other. The disorder causes mild to moderate anemia, but does not shorten life expectancy.

Diagnostic Studies and Procedures

Sickle cell disease is diagnosed by taking a family history and by hemoglobin electrophoresis, a blood test that can detect the abnormal red cells.

Medical Treatments

Anyone diagnosed as having sickle cell disease should be referred to a specialist in genetic blood diseases for future monitoring and treatment.

Experimental drugs that prevent sickling of the red blood cells are being tested; in the meantime, guarding against infection is a major focus of treatment. Specialists generally recommend that all babies diagnosed with sickle cell disease receive prophylactic antibiotics. Before this preventive treatment was instituted, 20 percent of children with this disease died before the age of three; now the mortality rate is less than 3 percent among children who are on long-term antibiotic therapy.

Immunization is also critical; in addition to the usual vaccines, pneumonia, influenza, and hepatitis immunizations are recommended.

Aplastic crises and their complications are treated as they arise. Blood transfusions are sometimes necessary to treat severe anemia. Supplemental oxygen may also be needed.

Alternative Therapies

Nutrition Therapy. Supplements of folic acid are often prescribed, but should be taken only under the supervision of a qualified nutritionist.

T'ai Chi. Running and other vigorous activities usually are precluded because sickle cell disease often damages large, weight-bearing joints. Tai chi, with its gentle exercises, helps maintain muscle tone and fosters well-being.

Self-Treatment

If you have sickle cell trait, exercise caution when flying. Travel in a plane with a pressurized passenger cabin and make sure that supplemental oxygen is available if you need it.

About 2.5 million African-Americans carry the sickle cell gene, or trait. Couples who are contemplating parenthood and are at risk for transmitting the disease may want guidance from a genetic counselor. For example, if both partners carry the gene, there is a 50 percent chance that any child they have will inherit one gene and also become a carrier. In each pregnancy, there is a 25 percent chance that the child will inherit two genes, and develop the disease, and also a 25 percent chance that the baby will have two normal genes and be free of the trait.

Other Causes of Abnormal Hemoglobin

More than 400 different hemoglobin disorders interfere with the blood's ability to transport oxygen. Thalassemia, a genetic disease that is most common among people of Mediterranean origin, has some of the same characteristics of sickle cell disease.