A misunderstood disease
Around 100,000 Americans are living with sickle cell disease, making it the most common inherited blood disorder in the U.S. Those who have the disease are born with it, though often, symptoms don’t appear until 5 or 6 months of age, when acute pain, fatigue andjaundice may develop. In the U.S., most people with SCD are African American, but the disease can also affect those from Hispanic, southern European, Mediterranean, Native American, Middle Eastern and Asian Indian backgrounds. Here are nine facts about SCD, from causes to treatment.
1. What causes it?
It’s all in the red blood cells — or more specifically, the hemoglobin, a protein in red blood cells that carries oxygen through the body. In most people, red blood cells are round and smooth, and they carry oxygen through small blood vessels. In those with SCD, red blood cells are shaped like a “C” and look like a sickle (a farming tool with a semicircular blade — hence the name), and they tend to get stuck and clog blood flow. When that happens, blood can’t get where it’s needed, and vital tissues and organs don’t have the oxygen they need to stay healthy.
2. How common is it?
Sickle cell disease is one of the most common genetic disorders in the world. Each year, 1,000 babies in the U.S. and 500,000 worldwide are born with it, according to the Sickle Cell Disease Association of America. The disease is especially prevalent among babies from certain parts of Africa, says Dr. Oswaldo Castro, professor emeritus of medicine at Howard University and an advisor to the university’s Center for Sickle Cell Disease. “Over 1 percent of babies from these areas are born with sickle cell disease,” Castro says.
3. Where did it originate?
According to the SCDAA, the disorder originated in at least four different parts of Africa and has since spread wherever else Africans have migrated. SCD entered the U.S. via the transatlantic slave trade, and today, the disease is found in most parts of the world, from Portugal and most of Europe all the way to Sri Lanka and southern India. SCD is still widespread in Africa — the disease affects at least 2 percent of the population in countries such as Cameroon, Republic of Congo, Ghana and Nigeria.
4. Is it contagious?
Sickle cell disease isn’t contagious — people are born with the disorder just as they’re born with physical characteristics such as eye color, height and blood type. It’s passed down when kids inherit two abnormal hemoglobin genes, one from each parent. When both parents carry the sickle cell trait, there’s a 25 percent chance their child will be born with SCD. A person who inherits the gene for sickle cell disease from one parent and a normal gene from the other has the “sickle cell trait.” For most people, this trait produces no symptoms of SCD.
5. What’s it like to live with SCD?
The symptoms of sickle cell disease appear at an early age and slowly become more unpleasant over time. Children with SCD suffer from painful swelling in their hands and feet, anemia (or low red blood cell count) and whitening of the eyes. Both children and adults are at risk for stroke. People with SCD can experience intense flare-ups of pain in their arms, legs, chest or abdomen called crises, and other complications include vision loss, gallstones, delayed growth and organ damage and failure.
6. How is SCD treated in children?
Since SCD worsens over time, treatment is a lifelong effort. Babies with SCD are diagnosed at birth and take daily doses of penicillin until age 5, when the risk of life-threatening blood stream infections decreases. Experts say it’s important for these kids to receive all childhood vaccines plus pneumococcus and meningococcus vaccines to help fight possible infections. Kids who are at a high risk for stroke are treated with monthly blood transfusions, which provide them with new, healthy red blood cells, Castro says. Though normal exercise is OK, frequent breaks are necessary to allow oxygen to travel through the body, preventing cells from sickling.
7. How is it treated in adults?
Those with chronic pain from SCD take hydroxyurea, an oral medicine that curbs pain by increasing the amount of hemoglobin in the blood. Patients undergo frequent blood and urine tests to check for symptoms such as anemia and kidney damage and are encouraged to follow lifestyle advice like staying hydrated (dehydration can cause red blood cells to sickle). The CDC suggests limiting alcohol consumption and getting plenty of rest after exercise, and it’s helpful to avoid the cold, since frigid air can trigger red blood cell sickling in exposed areas of the body.
8. Does it affect life expectancy?
Forty years ago, the average life expectancy of a person with sickle cell disease was 14 years. Now, in developed countries like the U.S., adults with SCD can live to be over 50 years old. “Adult sickle cell disease patients, however, still appear to live about 20 years less than non-sickle cell patients,” Castro says. The most common causes of death among SCD patients include bacterial infection, stroke or bleeding into the brain and organ failure.
9. Is there a cure?
Only one option offers any promise: a type of bone marrow transplant called hematopoietic stem cell transplantation, which involves transferring healthy, blood-forming cells from one person into the bone marrow of another. The procedure is mostly done in children prone to strokes and chronic pain, and it’s rare: Only 1 in 10 kids with SCD are able to find a donor. “The problem with bone marrow transplantation is that it’s safe and effective only if a related, tissue-compatible donor, usually a healthy sibling, is available,” Castro says. “Most patients don’t have such donors.”