Genetic Screening for Sickle Cell Sparks New Debate on Old Disease
Sickle cell anemia was first formally identified exactly 100 years ago this month. The disease involves a group of inherited blood disorders whereby red blood cells become hard and sticky and look like a crescent-shaped farm tool called a sickle, as opposed to their usual disc shape. The defective cells tend to cluster together when they travel through small blood vessels, causing a blockage in the blood stream and halting the movement of oxygen-carrying blood. These cells also die early, which leads to a constant shortage of red blood cells. People with Sickle Cell Disease (SCD) usually live into their 40s or 50s — roughly 30 years less than the average lifespan. It’s long been known that SCD is caused by a hereditary mutation in the hemoglobin gene passed to a child from both parents. But the disease is attracting fresh attention because American universities are now requiring top athletes to be tested for the gene that causes SCD. Colleges hope to prevent sudden deaths among young players, but some worry that a new wave of genetic screening could resurrect old prejudices. That’s because Sickle Cell Disease disproportionately affects African Americans in the United States. Worldwide, it tends to impact “populations that have limited access to comprehensive care due to social, economic, cultural and geographical barriers,” according to the Centers for Disease Control and Prevention. SCD is particularly common among people whose ancestors come from sub-Sahara Africa, Saudi Arabia, India and Mediterranean countries such as Turkey, Greece and Italy. Among the roughly 100,000 Americans affected by the disease, the majority are black, with SCD occurring in one out of every 500 African American births. Furthermore, the SCD trait is found in one out of every 12 African Americans. These people have the sickle cell trait — but not necessarily the disease and its symptoms. The prevalence of the disease among African Americans has prompted criticism that the college-screening mandate would unfairly target black athletes. “This amounts to a massive genetic screening program, with tens of thousands being screened,” Troy Duster, a sociology professor at New York University who studies the racial implications of science, recently told the Washington Post. “This could have an extraordinarily heavy impact on black athletes. You are going to be picking out these kids and saying, ‘You are going to be scrutinized more closely than anyone else,’” he said. “That’s worrisome.” Universities argue that if the gene is identified in these athletes, those who carry it could be watched more closely and their training tailored to prevent life-threatening complications from physical activity. For example, they could be given more time to rest or more water to drink. As of Aug. 1, all new students joining NCAA Division I teams must be tested for the sickle cell trait — a mandate that will affect about 170,000 student-athletes. No one will be restricted from playing sports based on the results of the test, which is conducted regardless of race. But the issue of race is hard to avoid. As the Washington Post article pointed out, “for decades blacks were stigmatized by sickle cell because they carried it far more commonly than whites, marking them as supposedly genetically inferior, barring them from jobs, the military, insurance and even discouraging them from marrying and having children.” The Sickle Cell Anemia Association of America along with a federal panel that advises the government on issues related to genetic testing have both questioned the decision to screen student athletes, although most doctors and school officials seem to support it. “The testing is being watched closely as a case study in both the potential benefits and risks of large-scale modern genetic screening, which is proliferating as the genetic bases for more and more diseases are being deciphered,” the Post’s Rob Stein wrote. At the same time, sickle cell manifests itself quite differently in different people, further complicating the issue. Some patients who’ve been diagnosed with SCD, for instance, have very few episodes of pain, lasting from a few hours to several days. Other people report painful symptoms several times a year, sometimes severe enough to require hospitalization. Sickle Cell Disease was first identified in 1910 by Dr. James B. Herrick, who published a report in the Archives of Internal Medicine describing the experience of a young student from Grenada attending dental school in Chicago. Soon after arriving, the student sought medical attention, and the abnormal shaped red blood cells in the student were noted in the report “Peculiar Elongated and Sickle-Shaped Red Blood Corpuscles in a Case of Severe Anemia.” Common sickle cell symptoms include painful abdominal attacks, bone pain, breathlessness, delayed growth/puberty, fatigue, fever, jaundice, pale skin, rapid heart rate and ulcers on the lower leg. Other symptoms include chest pain, excessive thirst, frequent urination, poor eyesight and blindness, painful and prolonged erection, stroke and skin ulcers. If a doctor believes you have SCD, aside from the usual medical checks, a blood test and other procedures are performed. In fact, many states provide routine newborn screenings for high-risk infants so as to begin proper treatment as soon as possible. (Symptoms do not usually surface until after a baby is at least four months old.) Early diagnosis is crucial in giving the proper care and preventative treatment for some of the disease’s more devastating complications. Usually, a patient is given a hemoglobin electrophoresis blood test, which can determine if a person is a carrier of a specific sickle cell trait, or if the patient has any of the disorders associated with the sickle cell gene. While there is no definitive cure for SCD, there are many ways to treat its symptoms. Doctors prescribe pain medications to help with flare-ups and penicillin to prevent inventions. They advise patients to drink eight to 10 glasses of water daily to treat and prevent pain. Folic acid is also required to help prevent severe anemia. Blood transfusions may also be needed to prevent stroke or anemia or to treat chronic pain and other emergencies. Bone marrow transplants may offer a cure in a limited number of cases. Although its long-term effects are unknown, doctors are also prescribing hydroxyurea, a recently developed medication that may help reduce pain and chest issues, while decreasing the need for frequent blood transfusions. In addition, there are various experimental studies and trials under way to help treat or even one day cure SCD. Among the trials, researchers are examining if butyric acid — which manufacturers normally add to food — may increase the amount of fetal hemoglobin found in blood. Other studies are looking at clotrimazole, an antifungal medication that helps reduce the loss of water from red blood cells, which may in turn minimize the formation of sickle cells, as well as nitric oxide, the gas found in our bodies that helps keep blood vessels open and reduces the stickiness of red blood cells. Another approach is turning directly to the source of Sickle Cell Disease. Gene therapy involves inserting a normal gene into a patient’s bone marrow to produce normal hemoglobin. Scientists are also investigating the idea of deactivating the defective SCD gene while reactivating another gene that produces fetal hemoglobin. This is the type of hemoglobin found in newborns and prevents sickle cells from forming. For now, however, the same advice that has been used for decades seems to work best: maintain a healthy lifestyle and take steps to prevent and control complications, including pain, through a comprehensive, multidisciplinary program of care and a strong extended support system.
About the Author
Rima Assaker is a freelance writer in Silver Spring, Md.