Gene therapy for haemophilia

Doctors have successfully used gene therapy in the treatment for a type of haemophilia, a condition caused by a defect in one of the genes which controls blood clotting. Sufferers bruise easily, are prone to nosebleeds, and have a risk of internal bleeding.

A virus that had been genetically altered to carry a working version of the defective gene was transfused into the livers of haemophiliacs. This inserted into the patient's DNA a working version of a gene controlling the manufacture of a blood clotting agent called factor IX. Following the transfusions, the patients were tested to see whether the newly-added gene had caused greater levels of the clotting agent to be produced. The researchers, based at the Children's Hospital of Philadelphia, US, found that levels of factor IX in the blood had risen sharply, enabling them to reduce or stop other treatments the patients were undergoing.

Katherine High, leader of the study, reported the findings at the annual meeting of the American Association for the Advancement of Science in Boston, US. She said that the researchers believe the results are encouraging, adding that 'advances in research and technology suggest that gene therapy will become a successful and powerful method of treating human disease'.