tokyo

The first clinical application of preimplantation genetic diagnosis in Japan moved a step closer last week with the approval by the ethics panel of Kagoshima University Medical School of a protocol for testing for Duchenne muscular dystrophy in human eggs fertilized in vitro.

A decision on whether to go ahead depends on the approval being confirmed by the Japan Society of Obstetrics and Gynaecology. The society last year opened the way to preimplantation genetic diagnosis in principle when it approved general guidelines covering such procedures (see Nature 394, 110; 1998 ). These allow couples to ask for eggs used for in vitro fertilization to be discarded if susceptibility to certain types of hereditary disorder is detected in the genes.

But the society came under fire, as its guidelines were seen as a poor replacement for a national debate on the ethical issues. Critics argued that legislation was needed to prevent such techniques being put to non-medical uses, such as selecting the sex of a child.

Akira Hira, principal of the university'smedical school and chairman of the ethics committee, says its decision was based on the safety and reliability of the technique, and the potential benefit it would bring to patients. But he admits that gaining public acceptance will not be easy. “There are still a lot of ethical and scientific questions we would have to explain to the public to gain their support and understanding,” he says.

Concern about the ethical implications of Kagoshima University'smove has been voiced by the anti-eugenics patients' advocacy group, which represents more than 30 womens' and disabled groups. They argue that prenatal diagnosis risks increasing discrimination against the disabled.

But Hiroyuki Nagata, professor of reproductive medicine at Kagoshima University, argues that early detection of genetic disorders would allow mothers undergoing in vitro fertilization to avoid ‘therapeutic abortions’.

The approved protocol involves a couple who already have a child suffering from Duchenne muscular dystrophy. “I feel that the protocol poses fewer ethical problems than prenatal genetic diagnosis [of fetuses] and therapeutic abortion does,” says Nagata.

The university originally approved the same protocol in 1995, but was forced to postpone a final decision because of opposition from patients' advocacy groups. Since then, the society has issued guidelines, and the latest proposals are based on them.

Opposition from patients' advocacy groups has similarly forced the Japan Society of Obstetrics and Gynaecology to postpone approval of specific guidelines for screening for Duchenne muscular dystrophy (see Nature 385, 763; 1997 ). The general guidelines approved last year do not specify which diseases can be tested for, but limit screening to serious diseases, and require case by case approval by a specialist committee of doctors and geneticists appointed by the society.

Keiko Yano, the director of the advocacy group, argues, however, that the ethical issues the technique raises require greater discussion before any further decision is made on the application of preimplantation genetic diagnosis.