Japan - Experts split over genetic diagnosis technique

Main Category: Public Health
Article Date: 02 Feb 2004 - 0:00 PDT


The medical community is divided over a proposal to approve preimplantation genetic diagnosis, a method for determining whether a fertilized egg has a genetic disease.

The Japan Society of Obstetrics and Gynecology is debating the pros and cons of the technique, which is designed to weed out genetically defective embryos. However, critics say the method could be misused as a form of vetting whether an embryo should be allowed to be born.

Opinion also was divided in discussions at the government's Council for Science and Technology Policy, though the panel decided to conditionally approve the genetic test late last year.

On Jan. 23, a couple who asked Nagoya City University to conduct preimplantation genetic diagnosis on them submitted a petition to the society.

Shortly after their marriage, the husband developed muscular dystrophy, an incurable disease that gradually causes muscular weakness.

The husband said, 'Now that I know it's a genetic disease, I don't want my child to suffer the same hardship.'

Although his wife was pregnant at one stage, the couple decided to abort the pregnancy after a medical check found that the fetus had inherited the disease.

Though the couple said they understood that preimplantation genetic diagnosis may lead to ethical and social problems, their petition described their deep feelings that they did not want their sorrow to be repeated and their wish for a healthy baby.

The society approved the technique in 1998 on the condition that it was allowed only for serious genetic diseases after screening by the society.

Nagoya City University and Keio University have applied for implementation of the technique for those with muscular dystrophy, and the society is screening their applications.

The medical society already has rejected two applications, including one by Kagoshima University, on the grounds that the clinical method and the diseases to be checked were inappropriate.

Differing from prenatal diagnosis, preimplantation genetic diagnosis does not result in an abortion. As a result, it can be described as a technique that allows parents to choose desirable fertilized eggs without the sense of guilt involved in terminating a life.

But the procedure also has sparked fears that it could lead to discrimination in the selection of embryos for birth.

An Osaka-based citizens network opposed to genetic manipulation recently submitted a letter of request to the medical society.

The network, which includes handicapped people, said in the letter that preimplantation genetic diagnosis would 'increase discrimination against people with diseases and handicaps. Discriminating between people by placing priority on their health must not be allowed.'

Some obstetricians and gynecologists have expressed their wish that the technique be available for another purpose. One such doctor said, 'It's effective for selecting the best eggs for fertilization treatment, rather than for the diagnosis of genetic diseases.'

In the United States, about 70 percent of preimplantation genetic diagnoses are carried out to increase the success of in-vitro fertilization. The technique also is used for gender selection.

Shohei Yonemoto, president of Center of Life Science and Society and an expert in life ethics, said: 'It's necessary to hold discussions based more on facts, such as the quality of the technique and debates in other countries.

'The medical society should be very careful in approving the treatment and should pay attention to people's opinions.'

Less burden on mothers

Preimplantation genetic diagnosis is a technique to select an egg without genetic disease, while prenatal diagnosis involves testing the fetus, such as by obtaining a sample of the amniotic fluid to determine if the fetus is genetically defective.

In the process of preimplantation genetic diagnosis, eggs are fertilized through in-vitro fertilization, after which one or two cells are removed from the embryo about two days after the process, when each embryo has divided to about eight cells.

Doctors then analyze the cells' genetic material, implanting in the woman's womb only embryos that are free of genetic disease.

Scientists have cited the benefits of the technique, such as allowing a couple with a possibility of producing a baby with hereditary genetic disease to not give up on having a healthy child.

In addition, prospective mothers can avoid having to undergo an abortion, which can cause severe physical and mental trauma.

The first preimplantation genetic diagnosis in the world was conducted in Britain in 1989.

According to the government council, 377 couples received preimplantation genetic diagnosis in 35 facilities in Western countries until 1997, and 96 babies were born as a result.

The technique is banned in Germany on the ground that it is a form of discrimination.

The diagnosis requires high-level medical skills. The accuracy rate is only 80 percent even in top Western medical institutions.

Medical experts said the diagnosis should be reconfirmed through an amniotic fluid check or other methods after pregnancy.

Debate said insufficient

A panel of experts on life ethics of the Council for Science and Technology Policy hammered out a policy to permit preimplantation genetic diagnosis only for serious genetic diseases in its interim report on the treatment of human embryos released in December.

Public symposiums planned to determine government policy over the issue are scheduled for Feb. 8 in Tokyo and Feb. 15 in Kobe.

The panel spent much of its time discussing whether producing cloned human embryos, which may lead to cloned humans, should be permitted, and other issues, during its debates in 21 meetings held over the past two years.

However, there has not been sufficient discussion on the issue of preimplantation genetic diagnosis. Though the panel has leaned toward permitting the technique under strict conditions, panel members are still divided over the issue.

Sophia University Prof. Saku Machino advocated the technique, saying: 'Currently, abortions are effectively freely available. It's irrational that preimplantation genetic diagnosis, which causes less burden on the mother's body, isn't permitted.'

But Tokyo University Prof. Susumu Shimazono was critical of the idea. 'Discussions of the issue haven't been sufficient, though we'll have a wider range of methods to screen out lives,' he said.

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