Hunting Down a Cure for Sickle Cell Disease
Excerpt By Janice Billingsley, HealthScoutNews

(HealthScoutNews) -- While a cure remains elusive, victims of sickle cell anemia are living longer, healthier lives.

The most common inherited blood disease in the United States, sickle cell anemia affects about 80,000 Americans, primarily blacks. Another 2 million Americans have the defective gene that causes the disorder, making them potential carriers.

Thanks to improvements in diagnosis, treatment and research, half of those with the condition are now more than 50 years old. Until recently, people with sickle cell rarely survived childhood, according to the National Human Genome Research Institute.

"I have five adult patients, one more than 60 years old, who watch out for themselves. They are good, cooperative patients who make sure they optimize their care," says Dr. Kenneth Algazy, a clinical associate professor of medicine at the University of Pennsylvania School of Medicine.

Sickle cell anemia is caused by the production of faulty hemoglobin, a key component of red blood cells. Hemoglobin carries oxygen from the heart to all parts of the body.

Once the hemoglobin molecules have released their oxygen, some can cluster to form long, rod-like structures. These rods cause the red blood cells to stiffen and to take on a sickle shape, preventing them from slipping through small blood vessels.

The resulting clots and blockages inhibit the flow of oxygen to the body's tissues and organs, particularly the lungs, kidneys and brain. The oxygen deprivation causes severe and potentially fatal complications, including stroke, Algazy says.

For the very few patients who have a sibling without sickle cell who are a genetically compatible match, a possible cure lies in a bone marrow transplant. The donor's healthy marrow lets the patient produce his own healthy hemoglobin, Algazy says.

"But that's very rare -- I've never had a patient with a match. Essentially, there is no cure," he says.

So researchers are turning to genetics. They are trying to correct the defective gene that causes sickle cell and insert it into the bone marrow of victims, to stimulate the production of normal hemoglobin.

Scientists at Harvard Medical School and the Massachusetts Institute of Technology reported last year that they had corrected sickle cell disease in mice using gene therapy, according to the Human Genome Research Institute.

However, such a cure is years away for human victims.

"Not in a year or two, but in five or 10 years there may be hope for a cure," Algazy says.

Another area of hope is drugs that increase the level of fetal hemoglobin in the blood. Fetal hemoglobin, found in fetuses and infants, stops the red blood cells from changing shape and helps ease the intense pain often suffered by patients.

Presently, only one drug, called hydroxyurea, is approved for this use. However, researchers at the University of Illinois in Chicago are studying another drug, called decitabine, which in a preliminary study increased the levels of fetal hemoglobin in all eight patients who took it on a daily basis for nine months.

None of the patients had found relief using hydroxyurea, says study author Joseph DeSimone, a professor of medicine at the university. With decitabine, all found their fetal hemoglobin levels rose approximately 11 percent to 14 percent.

A level approaching 20 percent is needed to reduce the symptoms of the disease, which can include intense pain as body parts are deprived of oxygen, he says.

"It worked well in terms of increasing fetal hemoglobin," DeSimone says, "and there was less red cell adhesion and less clotting."

Also encouraging was the absence of immediate side effects such as nausea, infection around the site of the injection, or rashes. The last is a common side effect of hydroxyurea, DeSimone says.

DeSimone and his colleagues are now starting a larger study of 30 to 70 people to test decitabine. SuperGen Inc., the drug's manufacturer, is funding the research as part of U.S. Food and Drug Administration approval trials.

"Sickle cell anemia is a lousy disease and can be very painful, and there are good things that are possible so people can go back to work and feel better," DeSimone says.

What To Do

September is National Sickle Cell Month.

To learn more about the disease, visit the American Sickle Cell Anemia Association or the National Human Genome Research Institute.

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