Sickle-Cell Disease
Sickle-Cell Disease
Sickle-cell disease is a genetically acquired disorder of the red blood cells. A person who inherits the sickle-cell gene from both parents is born with the disease; a person inheriting the gene from only one parent is a sickle-cell carrier. Sickling disorders in the United States are concentrated in areas where there are large groups of African Americans, such as the Northeast, Midwest, and rural South. Sickle-cell disease (a term preferred to the older "sickle-cell anemia") can also be found among the populations of West Africa, the Caribbean, Guyana, Panama, Brazil, Italy, Greece, and India. Eight percent of African Americans are heterozygous for the sickling gene or trait. These carriers may become ill at high altitudes, and some unexpected deaths have occurred to soldiers during extreme maneuvers. The gene for sickle-cell hemoglobin was first introduced to the Americas through the slave trade. Carriers of the disease have some immunity to the fatal form of malaria, something that proved useful to African slaves in swampy tidal regions, as in the Chesapeake and South Carolina.
The sickle cell, so called because of its bent shape, was not named until 1910, when J. B. Herrick described the blood cells of an anemic patient. In 1949 Linus Pauling discovered the chemical abnormality that causes red blood cells to become misshapen and also found the link between the sickle cell and malaria. Although the attention given the disease has increased substantially since World War II, misinformation about the illness persists and often causes discrimination against sickle-cell carriers in the insurance industry and the job market. In the 1970s the prevalence and consequences of sickle-cell disease became widely publicized in both the African-American and mainstream media.
Several organizations have been established for education and research about the disease, including the National Association for Sickle-Cell Disease, founded in 1971 in Los Angeles. Numerous hospitals have centers for the study of sickle-cell disease, including the Columbia University Comprehensive Sickle-Cell Center at Harlem Hospital in New York City, founded in 1972, and the Center for Sickle-Cell Disease at Howard University, founded by Ronald B. Scott in 1972. These organizations have undertaken extensive fund-raising campaigns for research and treatment of the illness. Government funding for research has risen since the early 1970s. Attempts to cut federal research support in the 1980s drew vehement opposition from many black organizations. In 1993 thirty-eight states and the District of Columbia required testing of newborns for sickle-cell traits, and the number now is over forty. Support organizations include the Sickle Cell Disease Association of America, the American Sickle Cell Association, The National Heart, Lung, and Blood Institute, the Sickle Cell Information Center, and the Joint Center for Sickle Cell and Thalassemic Disorders.
In persons with sickle-cell disease, deoxygenated hemoglobin S causes the red blood cells in the body to assume the sickle shape. These cells cannot carry oxygen as normal red blood cells do, and they lodge in small blood vessels, causing ischemia (oxygen deficiency) and necrosis. This blockage of vessels is called vasoocclusive crisis and gives rise to intense pain.
Symptoms of sickle-cell disease usually appear after six months of age when the last of the fetal hemoglobin, which increases oxygen supply in the blood, leaves the infant's body. Untreated, a patient may develop circulatory collapse. Such a patient is given large amounts of intravenous fluids to support circulation and prevent shock. Older patients may have pain in the larger bones, chest, back, joints, and abdomen and can develop hemorrhages into the eye and brain.
Treatment for sickle-cell patients commonly calls for pain medication ranging from oral analgesics to injectable narcotics for pain management. Intravenous fluids are prescribed to prevent dehydration and flood the vasculature with the intention of floating the sickling cells from occluded vessels. Antibiotics are ordered for infections, and prophylactic penicillin is suggested for infants to prevent infections. Blood transfusions are not routinely recommended for short-term crises but may be indicated during prolonged episodes and when lung and central nervous system involvement is evident.
Experimental treatment for sickle-cell patients includes the use of hydroxyurea, which can increase the level of fetal hemoglobin circulating in the body. Bone-marrow transplants have been performed on some children. This remains a risky procedure, however, carrying a 5 to 10 percent mortality rate. Though no cure exists, methods of treating chronic sickle-cell patients have improved in the past twenty years. Conservative treatment methods offer a prudent course of disease management. People with sickle-cell disease, once expected to live only to their forties, now live longer and healthier lives.
Bibliography
Edelstein, Stuart J. The Sickled Cell: From Myth to Molecules.Cambridge, Mass.: Harvard University Press, 1986.
Hill, Shirley A. Managing Sickle Cell Disease in Low-Income Families. Philadelphia. Pa.: Temple University Press, 2003.
Kiple, Kenneth F., and Virginia Himmelsteib King. Another Dimension to the Black Diaspora: Diet, Disease, and Racism. New York: Cambridge University Press, 1981.
Oski, Frank A. Principles and Practice of Pediatrics, 2d ed. Philadelphia, Pa.: Lippincott, 1994.
jane m. deluca (1996)
Updated by publisher 2005