COVER

PREVENTIVE MEDICINE

TESTING FOR DEFECTIVE GENES

TOM FENNELL July 15 1991
COVER

PREVENTIVE MEDICINE

TESTING FOR DEFECTIVE GENES

TOM FENNELL July 15 1991

PREVENTIVE MEDICINE

COVER

TESTING FOR DEFECTIVE GENES

For the past three years, Carol-Ann Szwarz, a Burlington, Ont., mother and former social worker, has fought a nightmarish battle with Tay-Sachs disease, a disorder that affects the central nervous system and inevitably leads to paralysis and death in childhood. Two years ago, Szwarz’s first child, Jennifer, died of the disease at the age of 3. The technology of genetic testing has advanced to the point that the molecular analysis of fetuses as young as nine weeks can reveal the presence of the malevolent disease. As a result, Szwarz, 30, had two abortions after testing revealed the presence of the disease in her unborn children. But she also gave birth to two healthy sons, Matthew, 2, and Jordan, who is now eight weeks old. Said Szwarz, founder and vicepresident of the National Tay-Sachs and Allied Diseases of Ontario Inc.:

“There is no reason why a person has to give birth to a Tay-Sachs child. If I had my way, everyone would be screened for it.”

Future: Increasingly, genetic science can play a role in a child’s future almost from the time a doctor tells a woman that she is pregnant. With genetic testing now available at many major Canadian hospitals, more and more couples are having fetuses tested for a growing number of genetic disorders, including Tay-Sachs, cystic fibrosis and thalassemia, a hereditary blood disease that can be fatal. If the fetus carries a defective gene that could lead to disease, the parents can decide whether or not to abort the pregnancy, or in some cases doctors can attempt to treat the illness.

So far, genetic screening can detect the presence of genes that cause about 200 diseases. In a report published in June following a five-year study of genetics in Canadian health care, the Science Council of Canada predicted that the use of genetic testing will increase dramatically during the next five years. Said Charles Scriver, a professor of genetics at Montreal’s McGill University who headed the Science Council committee that carried out the study: “Genes probably have something to do with virtually every disease.”

For that reason, Scriver says that the potential of genetic testing is almost limitless. Some experts at the Vancouver-based Canadian Genetic Diseases Network, which links medical geneticists across Canada, estimate that screening will eventually be able to pinpoint more than half the defective genes that

are responsible for about 4,000 different genetic diseases. The diseases range from hypertension and certain types of cancer to alcoholism and some psychiatric disorders. Geneticists also say that about 60 per cent of the Canadian population will at some point in their lives contract a disease that has a genetic component, and that faulty genes account for about one-half of all infant deaths in Canada. Said Michael Hayden, director of the Adult Genetics Clinic at the University of British Columbia in Vancouver and the network’s scientific director: “I think that we are going to be predicting and treating diseases earlier to im-

prove the quality and longevity of life.”

But each advance in genetic knowledge and screening technology raises troubling emotional and ethical questions, including those surrounding abortion. Some critics also say that genetic screening opens the way for the practice of eugenics, a pseudoscience developed during the 19th century that proposed improving the human race through selective breeding. Some aspects of eugenics were put into practice during the 1930s and 1940s by Germany’s Nazi rulers, who ordered the extermination of millions of Jews, gypsies, homosexuals, mental patients and other members of groups that the Nazis considered inferior.

Now, critics of genetic screening argue that the new technology merely puts a human face on eugenics, because ultimately it will allow parents to abort fetuses that have even the slightest defect. Genetic screening, said Stephen Jalsevac, a director of the Toronto-based Campaign Life Coalition, which opposes abortion, is “a very serious and ominous develop-

ment” that could allow “search-and-destroy missions” against defective fetuses.

As a result of the genetic revolution, relatively simple laboratory procedures mean that much of an individual’s medical future can be read in his genes. In one type of test to determine whether a person carries a defective gene, technicians take a sample of the patient’s deoxyribonucleic acid, the material in human cells that carries an individual’s genetic blueprint. Technicians use chemicals to cut the DNA into smaller pieces, which they then saturate with radiation and mix into a medium containing a second DNA sample that has been cloned,

or copied, in a laboratory and which includes the genetic defect that the technicians are searching for. If the two genes bond in a specific way, scientists know that the defective gene is present in the patient and can follow it by its radioactive signal.

Dollars: Geneticists say that as the use of testing grows, it will shift the emphasis of medicine away from treatment to prevention. Hayden, for one, said that as genetic testing makes it possible to identify more diseases, physicians will be able to identify patients who are likely to develop diseases in the future. If a patient has genes that make him particularly susceptible to heart disease, his physician will then be able to urge preventive measures to slow the onset of disease by, among other things, trying to limit the patient’s smoking and cholesterol consumption. Said Hayden: “I would predict that by the turn of the century, a

lot more of the health-care dollars are going to be put into prevention and prediction, because it is cost-effective.”

Even though genetic testing is still years away from reaching its full potential, it has already brought relief to individual Canadians who feared contracting a genetic disease that was present in their families. Terrance Connolly, a 64-year-old retired physical education director who lives in Vancouver, says that his older brother has Huntington’s disease, a degenerative nervous-system disorder. Connolly said that if he also had the Huntington’s gene, then his two children would have a 50-per-cent chance of being affected as well. But Connolly said that after he submitted to genetic testing last year at the UBC University Hospital, he learned that he was free of the defective gene. Said Connolly: “We had a quiet celebration.” Parents who are often overwhelmed by feelings of guilt when their children are bom with genetic disorders have been aided by the improved diagnostic technology that at least prepares them for the grim reality. Jacqueline Cacciotti, a 40-yearold Toronto flight attendant, did not have her fetus tested and now has a two-year-old daughter, Kristen-Ashley, who was bom with a rare genetic form of cancer. Said Cacciotti: “At first, I blamed myself. I wondered what I did wrong.” According to Jennifer Fitzpatrick, a genetic counsellor at Toronto’s Hospital for Sick Children, parents in situations like Cacciotti’s often feel guilty. Added 5 Fitzpatrick: “People feel that § if they do everything right in I their pregnancies, then they 5 are guaranteed to have a

healthy baby. It is sad, but things go wrong.” As genetic testing becomes more common, says Ronald Worton, geneticist-in-chief at the Hospital for Sick Children, genetic screening technology will confront individuals with cruel choices. Genetic testing, he said, could make it difficult for a young couple to decide whether or not to go ahead and have a child that they know will be bom with cystic fibrosis. “They really do not know what cystic fibrosis is,” said Worton. “And reading a pamphlet is not going to help.”

Choice: Ethical decisions will become even more difficult when genetic testing detects the presence in a fetus of diseases that are not lifethreatening, but produce a child that is less z than perfect. According to Worton, parents in 5 the future might have the option of aborting ! fetuses because the unborn baby, while normal § in other ways, has subnormal intelligence or a ? cleft lip and palate. Said Worton: “While I’m I not in favor of abortion, I know in our profes“ sion we believe that it should be a matter of choice for the individual.” Some women who have given birth to children with genetic disorders say that they are not sure whether they would have wanted their child to be bom if they had known beforehand. Said Cacciotti: “If I was told when I was carrying Kristen, I really don’t know. I don’t know.” Some medical experts say that because of the difficult choices that genetic testing can force on couples, parents should be shown all the alternatives to abortion, including possible treatments and dealing with the birth of a mentally or physically handicapped child. “We need to teach people that it is all right to have a handicapped child,” says Françoise Baylis, a bio-ethicist at the Hospital for Sick Children.

Ultimately, spiralling health-care costs may limit the use of genetic screening in Canada at a time when dramatic breakthroughs are increasingly possible. In its report last month, the Science Council of Canada said that not enough money is being allocated to develop genetic testing clinics. The report concluded: “If the Canadian public is to reap the benefits of genetic knowledge and technologies, genetics must be given a higher priority in our health-care system.” It added: “All health-care practitioners must become, to some degree, geneticists.” Some geneticists go further, arguing that governments should finance major research into genetic testing to protect the nation’s medicare system. Said Scriver: “Our healthcare system will not be equitable because it does not contain the resources to deal with the genetic causes of diseases in the population, and they are everywhere.” He added: “We will spend $100,000 to fix a person up who has had a heart attack, but we do not appear to be willing to spend a penny to identify the person who is at risk and derail the disease through preventive measures.” Despite that, the benefits that Carol-Ann Szwarz and others have gained from genetic testing suggest that the new technology is certain to play an important role in the health care of the future.

TOM FENNELL