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Simple Test Can Help Identify Genetic Blood Disorder - 2002-10-11

In Pakistan and other countries in north Africa, the Middle East and Asia, it is common for cousins to marry. Unfortunately, researchers say, intermarriage of close family members can result in a fatal genetic blood disorder. But a study conducted in Pakistan shows a simple blood test and counseling may help to curb the disease.

About five percent of the population in Pakistan has a genetic disorder known as beta-thalassemia. Married couples who each carry the gene for thalassemia have a 25 percent chance that any child of their's will carry the disease.

In a study of extended families of thalassemia carriers published in the New England Journal of Medicine, researchers found an even higher rate - 31 percent.

Mary Petrou, an obstetrician/gynecologist at the Royal Free and University College Medical School in London, led the study. Dr. Petrou says people with thalassemia cannot make red blood cells, which carries oxygen around the body. "Now, treatment of thalassemia in Pakistan is very, very difficult, first of all because there's a large number of patients and also because blood resources are low," she said.

While patients are very small children, Dr. Petrou explains, blood transfusions work to replace red blood cells. But as they get older, blood transfusions become harmful. "Therefore, what happens to these children? By the time they get to their teens, they would be suffering from iron overload, and this is because of the excess iron building up in the body because of the repeated blood transfusions," said Mary Petrou. "And they usually die due to cardiac failure."

Dr. Petrou says there's a drug to treat thalassemia, but it's extremely expensive - about $4,000 per patient or 10 times the average annual income. The result, she says, is that most families in Pakistan cannot afford to treat their offspring.

So, Dr. Petrou and colleagues wanted to see what impact a simple blood test would have on the decision of married couples to have children with the potential for thalassemia.

Researchers studied 10 families with a history of the blood disorder. They tested children, parents, grandparents and anyone else in extended families who was still alive.

All carriers of thalassemia and parents found to carry the gene received counseling.

Dr. Petrou says all carriers were receptive to counseling about the risk of passing on thalassemia. "The ones that had at least two healthy children, they limited the children so that there was no further children amongst these families," she said.

Antonio Cao is a professor of pediatrics in Caliari University in Sardinia. Professor Cao says, in a poor country like Pakistan, where thalassemia is so widespread and other problems, like malnutrition and hunger are great, many families affected by thalassemia would not be identified through a limited screening program.

That's because it's common for children to die of unexplained causes. "So they are only able to pick up only a limited number of families at risk," he said. "Because many children... they don't have the correct diagnosis."

Dr. Cao says a large, country-wide thalassemia screening program, supported by the World Health Organization, is needed in Pakistan and elsewhere.