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The scenarios in Our Genes/Our Choices present only a few of the many ways in which new genetic technologies affect people's lives. The three activities below suggest other ways to think about how genetic information affects both individuals and society at large.

How to Behave in a Brave New World

Every day genetic technologies present people with wrenching dilemmas, like the ones you've seen in the Our Genes/Our Choices programs. Often no easy answer presents itself, and any personal choice is likely to affect others. One of the keys to ethical thinking in these conditions is to consider all the parties who have something at stake, and to keep in mind that there are often many ways to arrive at a decision, as well as multiple resolutions. Dr. Mary Ann Cutter's essay, Should We?, shows how you might structure your thinking in order to assess the different positions of all the stakeholders involved.

The National Cancer Institute estimates that about 1 in 8 women in the United States will develop breast cancer during her lifetime. Tests can screen for dysfunctional forms of the BRCA-1 and BRCA-2 genes, which are associated with an increased chance of developing certain forms of breast cancer. But the implications of the test are far from clear-cut. Multiple genes play a role in cancer; having the dysfunctional form of the gene doesn't mean you will absolutely get the disease, in part because other genes play a role and in part because personal habits and the environment are important as well. Some individuals who have cancer-related forms of BRCA-1 and/or 2 do not go on to develop breast cancer, and individuals who have healthy forms of these two genes may still be at risk for breast cancer.

Suppose that 37-year-old Brenda works for a company that offers free genetic screening for breast cancer. Her husband wants her to be tested. Her mother, concerned about the possible repercussions for her and other family members, recommends against it. Brenda's doctor recommends more frequent mammograms in the event of a positive result, while her gynecologist recommends a radical mastectomy.

  • Should she have the test?
  • Who should have access to the results—and who else might obtain them?
  • How could Brenda go about making her decision?
  • How should she evaluate her family history, and take into account the opinion of close relatives and her doctor?

Make a list of all the possible stakeholders. See if you can convincingly argue the point of view of each. Can you figure out an outcome satisfactory to all? Can you arrive at multiple "fair" outcomes?

What Are the Odds?

If performed properly, and double-checked, a genetic test yields a result based in fact. However, interpreting the test result and determining what it actually means, is seldom a black-and-white proposition. It is one of statistics and probability. Because most diseases—or human traits for that matter—are influenced by many different genes, virtually everyone on the planet is likely to have certain susceptibilities. If enough tests were available, genetic "deficiencies" could be found in all of us. Whether or how they affect a person's health depends on many complex factors, from the way in which multiple genes interact to where that person lives, works, and eats. It's a question of understanding a range of possibilities.

Comparing several scenarios can help show the role probability plays in genetics.

  • Huntington's disease is a degenerative brain disorder that is controlled by a single dominant form of the gene. Anyone whose parent has the disease has a 50/50 chance of inheriting the disease form of the gene. If the children inherit the defective gene, they will certainly develop the disease at some point; the gene is what geneticists call "100 percent penetrant."

  • Cystic fibrosis is a lung disease that affects young people and is almost always severe. A defective gene causes thick mucus to build up in the lungs of CF sufferers. Their lungs deteriorate and ultimately fail, causing death. The gene is recessive, so both parents must carry the allele in order for the disease to be passed on. Each of their children has a 50 percent chance of being a carrier, a 25 percent chance of inheriting the defective gene from both parents and having CF, and a 25 percent chance of being free and clear. (Although it's tempting to think that if the first child has CF, the second is less likely to, these probabilities remain the same with each toss of the reproductive coin).

  • At a third level are the vast majority of diseases influenced by genetic factors, for which the probabilities are nowhere near as definitive. The numbers for Huntington's disease and cystic fibrosis are based on simple mathematical evidence and genetic rules. But predicting whether someone will come down with a disease like cancer or heart disease, which are caused multiple genes interacting with the environment, is extremely difficult. The result is probabilities like a "one in ten chance" of getting a certain disease: a number that is helpful for demographers but harder to interpret in terms of personal risk. Moreover, these estimations change as more is learned about a particular disease or about a particular patient's circumstances.

The best way to safeguard your health is to understand your own risk factors and to be an active patient. Do a chart of your family history. Is there a history of conditions like Parkinson's or heart disease? Make a list of the environmental factors—positive and negative—that might have affected these outcomes. Visit the Web sites of the National Cancer Institute (http://www.cancer.gov/cancer_information/), the Cold Spring Harbor Laboratory (http://www.yourgenesyourhealth.org), and other disease-specific sites to get a clearer idea of the risk your nature and nurture present you with. Talk to your doctor about what diagnostic and preventive steps will keep you as healthy as possible.

Genetics in the News

The field of genetics is evolving with extraordinary speed, generating new information, therapies, and theories all the time. Fifteen years ago, expectant mothers could undergo amniocentesis to be tested for a handful of genetic conditions such as Down's syndrome and Tay Sachs disease. Genetic counselors can now request screening for hundreds of conditions, and the list is growing fast. Likewise, the list of conditions in which genetics is known to play a significant role has expanded to include schizophrenia, resistance to AIDS, and some forms of cancer.

But it's often hard to understand the implications of genetic information. Media coverage can be misleading, as in the 1984 discovery of the BRCA-1 gene, which is strongly associated with a hereditary form of breast cancer. The news led many to fear that genetics was destiny, despite the fact that this particular gene accounts for less than five percent of breast cancer cases.

Likewise, the use of stem cells and therapeutic cloning raises hopes of treating diseases from Parkinson's to heart disease, despite the fact that these technologies are unlikely to offer anything to the medical consumer for the foreseeable future. Nevertheless, media attention swirls around them, fueled by ethical controversies and the science-fiction-like scenarios that they may some day make possible.

Choose one of the five conditions listed below and track media coverage over the past decade. List the milestones in understanding the genetic and environmental contribution to these conditions, or any others that are of special interest. What are the implications for health policy, research funding, and medical treatments?

  • asthma
  • obesity
  • autism
  • heart disease
  • alcoholism


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