No Easy Answers

Gina's brother Bill urged her to take the test. Bill had colon cancer and had just learned he had a genetic mutation in the MLH1 gene. There is a known correlation between the two: If Gina had the same mutation she had an 80-percent risk of developing colon cancer.

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At first Gina, 45 and the mother of three children in their twenties, wasn't sure what to do. Did she have an obligation to take the test? Did she even want to know the results? Could there be any harm in finding out the truth?

She went to see a cancer genetics team of counselors and doctors and decided to take the test. Later, she decided she did not want to know the results. Depressed, she didn't think she could handle it and refused further contact with the genetics team. Meanwhile the results came back positive: Gina had the mutation.

Although hypothetical, Gina's case could easily have been handled by Maria Mascari, a genetics counselor and medical geneticist at the Penn State Cancer Institute, and an assistant professor of pediatrics. It demonstrates one of the many dilemmas faced by medical geneticists: Does a person have the right not to know genetic test results, at the expense of his or her personal health? Does Gina's right not to know outweigh the rights of her children to know, since her testing positive puts them at increased risk for the mutation? Her children are young enough that prevention methods, such as adopting a healthier lifestyle and undergoing early screening for colon cancer, may reduce their risk of cancer.

"There are no easy answers to these questions," said Mascari, who discussed "Genetic Testing: Ethical, Legal, and Social Issues" in the Frontiers of Science lecture series. "As of right now, most, if not all, counselors and doctors would respect her right not to know," Mascari said, "but recommend that she and her children have regular colon examinations based on the family's history."

With the first draft of the human genome sequence now in hand, genetic applications are moving from the laboratory into everyday life. "There's no doubt that the future of medicine is going to depend very heavily on discoveries yet to be made regarding the human genome," said Mascari. "Every medical specialty will be impacted by these discoveries."

Of course, not all genetic testing is new. Screening newborns for the genetic disorder PKU has been done since the 1960s. PKU prevents a person from metabolizing phenylalanine, a chemical found in protein foods such as milk and eggs. The phenylalanine builds up in the blood stream, causing severe brain damage. A newborn diagnosed with PKU is immediately fed a formula low in phenylalanine and continues on a special diet into his or her adult life.

Another kind of genetic testing, carrier screening, tests adults to learn if they are carriers for hereditary diseases like cystic fibrosis; it has been common since the early 1990s. Cystic fibrosis affects one out of every 2,500 U.S. Caucasians. Its thick, pasty mucous secretions cause respiratory and digestive problems, usually leading to an early death. For a person to be born with cystic fibrosis, both parents have to be carriers—they do not necessarily have the genetic disorder but carry, and can pass on to their children, one copy of the mutated gene that causes it. An estimated one out of every 25 U.S. Caucasians is a carrier. "So if there are one hundred Caucasians in this room, you can do the math," says Mascari, "and the majority of people don't even realize they are carriers because there is no family history."

A genetic disorder can become an unintentional family legacy, unwittingly passed along. One solution is mass population screening: All adults get tested for cystic fibrosis. Then carriers could make informed family planning decisions.

The problem: Screening tests are not 100 percent accurate. They aren't as simple, or as cheap, as a home pregnancy test—pink for positive, blue for negative; the standard genetic test for cystic fibrosis must search out many genetic changes, since hundreds of different mutations have been found on the responsible gene. At the moment, tests can accurately identify 90 percent of these mutations—which means one out of every ten carriers will not be detected. "The worst thing is if a person who tested negative does not understand that there is still a small chance he or she could be a carrier," said Mascari. "At the moment, we do not have enough genetic counselors to provide appropriate education before and after testing for there to be a mass population screening."

But the test that "will most likely have the greatest impact on most of our lives," said Mascari, is called predisposition testing. The test tells if a person is predisposed, or more likely to get, a certain disease, such as diabetes or Alzheimer's. The test has also been used to look for mutations in the BRCA1 and BRCA2 genes, mutations linked to breast and ovarian cancer.

Not only do the outcomes of these tests worry people, but also the confidentiality: Who has access to the results? Can an employer find out a woman is predisposed for breast cancer and fire her? Can a man predisposed to colon cancer lose his insurance? Such concerns fall under the category of genetic discrimination: "social or economic discrimination based on one's hereditary predisposition to disease." Right now 33 states have enacted laws protecting people from genetic discrimination. "Unfortunately," Mascari noted, "Pennsylvania is not one of them."

In addition to personal concerns, genetic screening brings up family issues. For instance, what should an expectant mother do if she knows her baby will have the BRCA1 mutation? Said Mascari, "If you knew a child of yours would be predisposed to develop breast cancer, is that something you would want to have a prenatal test for, and maybe choose not to have the child? Is 40 to 50 years not worth living because ultimately that person is going to get breast cancer?"

The only way to resolve these issues is through continued education and thought. "Having this knowledge is one thing, but what's very important is that we make sure we apply this knowledge in a very ethical manner," Mascari said. "We need to develop methods to educate individuals about the benefits, limitations, and risks of that knowledge."

Maria Mascari, Ph.D., is assistant professor of pediatrics in the College of Medicine, Milton S. Hershey Medical Center, 500 University Dr., Box 850, Hershey, PA 17033; 717-531-1631; mmascari@psu.edu.

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Last Updated September 01, 2001