Fetal gene therapy on the horizon?

Doctors may one day be able to use gene therapy to treat fetuses affected by genetic conditions, say UK scientists. Researchers at Imperial College, University College and the Royal Free Hospital, all in London, have successfully used gene therapy to treat unborn mice affected by haemophilia B. Simon Waddington, of Imperial College, presented the team's results at the first annual meeting of the British Society for Gene Therapy, held in Oxford this week. The scientists now plan to assess the safety and ethical issues associated with using the technique in humans, according to a report in the Daily Telegraph newspaper.

People with haemophilia, nearly always boys, bruise easily and bleed for longer if they injure themselves. Haemophilia B is caused by a missing or faulty version of an X chromosome gene, which makes a crucial blood clotting protein called Factor IX. Dr Waddington and colleagues used an adapted version of the human immunodeficiency virus (HIV), altered so that it can no longer cause disease, to deliver a working copy of the Factor IX gene to mouse fetuses with haemophilia B. Waddington said that gene therapy in the womb (in utero) was now advancing to where it could be considered on patients in special circumstances. He cited cases where a genetic disorder is diagnosed during pregnancy, but where the parents do not wish to terminate the pregnancy, for religious or personal reasons. Charles Rodeck, of University College, went further, saying that fetal gene therapy could provide another option for affected families, apart from terminating or continuing with an untreated pregnancy. 'We would like this to be a third option - perhaps the best option' he said.

Professor Charles Coutelle, head of the gene therapy research group at Imperial College, said that it would be years before human fetal gene therapy trials could be considered. But if the approach is shown to be safe and efficient in larger animals, such as sheep, then it could offer hope for new treatments for diseases such as muscular dystrophy and cystic fibrosis. It is thought that fetal gene therapy might be more successful than treating children, since it would be easier to target more of the affected tissue, and there would be less chance of serious immune reactions.

A spokesperson for the Department of Health said that the researchers would need permission from both the Gene Therapy Advisory Committee (GTAC) and the Medicines and Healthcare products Regulatory Agency (MHRA), before carrying out a human fetal gene therapy trial. Charles Coutelle said: 'We would like another five years to make decisions about which diseases and which vector [gene delivery system] to choose, so we can do all the necessary safety tests we and the regulatory bodies think are required'.

A 1998 GTAC report on gene therapy in utero said that this approach did not raise any new ethical issues, compared to other medical treatments carried out in the womb, or the use of gene therapy in other situations. However, GTAC cautioned that existing concerns over the potential for germ-line transmission (the genetic alteration of egg or sperm-producing cells) remain. 'Such concerns would need to be fully answered in the event of any protocols proposing in utero gene therapy being presented to GTAC', the report concluded.