[Science Report]:Gene Therapy to Treat Hemophilia


This is the VOA SpecialEnglish Science Report.

American researchers report limited success using gene therapy totreat the genetic blood disease hemophilia.

Hemophilia results when a gene fails to produce the proteinneeded for the blood to clot, or change from a liquid to a solid.The defective gene is passed from parents to children. People withhemophilia suffer uncontrolled bleeding. This can result in pain,tissue swelling and permanent damage to joints and muscles.

One in every ten-thousand males has the most common kind ofhemophilia. It is extremely rare for females to have it. Patientscan be treated with the missing clotting substance. They generallycan lead normal lives.

Scientists say gene therapy may be a possible way to curehemophilia in the future. Most gene therapies use a virus to place agood copy of a gene into a cell that needs it. The new gene helpsthe body operate normally. For people with hemophilia, this meansthat clotting genes placed in the body would result in blood cellsthat clot normally.

Researchers consider hemophilia the best disease for gene therapybecause it is caused by a single defective gene. Also, only a smallincrease in the missing clotting substance could provide goodresults. Scientists at the Beth Israel Deaconess Medical Center inBoston, Massachusetts carried out the experiment. They reported theresults in the New England Journal of Medicine. They tested genetherapy in six patients with severe hemophilia.

First, they removed skin cells from the patients' arms. Theresearchers grew the cells in the laboratory. They added copies ofthe needed gene taken from healthy people. Then they createdhundreds of millions of genetically changed cells. They placed thesecells into the patients' stomachs.

After four months, the amount of blood clotting substance in theblood increased in four of the six patients. Some of the patientsreported a decrease in bleeding problems. However, ten months later,the clotting substance was no longer in the patients' blood. It isnot clear if the implanted cells died or the added genes stoppedworking.

The researchers say the study showed that gene therapy is safefor people with the most common kind of hemophilia. But othersexpressed concern about the treatment because the effects were onlytemporary.

This VOA Special English Science Report was written by NancySteinbach.

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