Sickle cell anemia is caused by a genetic change in one of two proteins, called the beta chain, that form the hemoglobin molecule, says Thomas W. Loew, MD, hematology/oncology at University of Iowa Children's Hospital.

"It is the hemoglobin molecule that actually attaches oxygen from the lungs and carries it, inside red blood cells, to the cells of the body. Because of the genetic change sickle, hemoglobin is more unstable and can form into a solid by precipitating inside the red blood cell," he says.

"When this process reaches an irreversible point, all the sickle hemoglobin in the red blood cell forms a polymer (multiple solid layers). This changes the shape of the red blood cell to the classic sickle shape (like the sickle on the Russian flag) that we see under the microscope. These sickle shaped cells do not travel well through the tiny blood vessels, called capillaries, thus blocking blood flow to the cells of the body. The result is a loss of oxygen and nutrients to the cells. This is what gives the painful crises and other complications associated with sickle cell disease."

Sickle cell anemia's hallmark symptom is painful crises. These can begin as early as six months of age. Individuals with sickle cell disease also have jaundice (yellow sclerae called scleral icterus), anemia, and abnormally shaped red blood cells. Sickle cell anemia can be complicated by cerebrovascular stroke, lung infarction or crisis, growth delay, priapism, a predisposition to certain severe infections and early death.

About 10 percent of African Americans are carriers of the sickle cell gene. Less than one percent of African Americans actually have sickle cell disease, which means all of their hemoglobin made is the sickle cell hemoglobin.

Loew says the sickle cell gene is also seen in other populations such as Middle Eastern people and some Hispanic populations. Other forms of abnormal hemoglobins, similar to sickle cell, can be found in people of Asian and Indian descent. All of these abnormal hemoglobin forms, in their carrier state, make the person more resistant to the effects of malaria, which is endemic to the areas of the world where these hemoglobins developed - Africa, the Middle East, India and southern Asia.

"All of these abnormal hemoglobins can be detected in the unborn child. However, newborn screening is the most common method of identifying infants with trait or disease. All 50 sates now include hemoglobinopathies as part of their newborn screening programs," says Loew.  

According to Loew, the use of dally prophylactic penicillin has significantly reduced the risk of infection and early death. He says hydroxyurea has been shown to reduce the frequency and severity of painful crises. "Many other therapies are being developed to treat the symptoms and complications of sickle cell disease. Good general care and close follow-up at a sickle cell center are important for preventing complications.

"Currently, therapy is focused on treating the symptoms of sickle cell disease. Bone marrow transplant is available to some patients with a matched brother or sister who can act as a bone marrow donor. Blood transfusions are sometimes required for treatment," he says.

The number of therapies focused on the symptoms of sickle cell disease is expanding says Loew. "Recently, the oral iron chelator, Exjade, was approved for individuals with Sickle Cell Disease who are on a blood transfusion program to reduce the risk of iron overload. Gene therapy is still a future possibility.

"There are a number of educational tools and support groups such as the Sickle Cell Disease Association. In addition, the UI Hospitals and Clinics program provides education, comprehensive care, and Camp Sunshiny Day - our summer camp for children with Sickle cell disease and related disorders.

"We are currently a participating site for an international clinical trail, the ASSERT trial sponsored by Icagen Corporation. We are looking at the use of their new drug, ICA-17043. The drug is designed to decrease the frequency and severity of painful crises. Our center has screened four patients and enrolled two. We are trying to screen two to four more patients in the next month before the study closes," he says.

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