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Genetic Testing Dilemmas

  • By Peter Tyson
  • Posted 03.08.12
  • NOVA

Scenario 4: Getting a Direct-to-Consumer Genetic Test

You feel fine, and you don't have a strong family history of any single disease, but you're curious about what your genes can tell you. You may want to know, for example, what your lifetime risk might be for developing certain common diseases or for passing defective genes onto your children—or perhaps more mundane things such as whether you have a gene that makes you sneeze in the sun. Instead of consulting with your doctor or a genetic counselor, you want to try testing on your own with a direct-to-consumer (DTC) genetic test from one of the companies now offering them.

You realize that DTC genetic testing is still in its early days, and such tests only look for the most common genetic markers—bits of DNA that vary from person to person and have been associated with an increased risk of a particular disease. If you have a strong family history of breast cancer or other serious disease, you would want to order a more comprehensive screening through your doctor, not rely on a far more limited DTC test. You also understand that DTC tests are all about probabilities, not guarantees, and that even if you have a mutation linked to heightened chances of getting a disease, you may never get the disease.

Close-up of DNA sequencing gel

Given the above information, would you get tested through a DTC genetic testing company?

Once you make this initial choice, you will have a chance to review some key issues that people typically consider. Then you can choose again—and see how others felt.

Now consider the following and then decide again afterwards:

knowledge can be power

Some prefer to know what their risk factors are, so they can better prepare for what might be coming later in life:

"I'm glad I took the tests. I went on a trip into my past, present, and future. It's an experience that gave me a new perspective on life. …[M]aybe it will help me someday, when I'm trying to piece together my medical mysteries." —Boonsri Dickinson, a reporter for Discover Magazine, who underwent DTC testing through three different companies

knowledge can also be a burden

For others, the emotional strain that would come with potentially learning that one had a genetic mutation or other variation that increases risk of disease would not be worth it:

"You know, I almost feel better not having genetic testing than knowing, oh my oh my, I have these mutations on these genes. … So are you going to sit there waiting for a time bomb to go off? When is it going to happen? Is it going to happen? No, I am not going to live that way." —Anonymous

many are concerned about privacy

Companies offering DTC tests typically promise confidentiality, an issue of great importance to many clients, some of whom do not want even their doctors to know their results:

"Finally we found a lab that … allows the patient to do the entire thing—confirm or rule out hemochromatosis [a build-up of iron in the tissues that can result in heart failure, diabetes, and other serious conditions]—and basically diagnose yourself. … So, a person can order the testing themselves, get the results themselves. No one else gets the results or sees them." —Anonymous

expert guidance is valuable

Many people feel it's important to have personal contact with a genetic counselor:

"The Internet is wonderful, and it can also be dangerous. Sometimes too much information, when you are not able to handle it, can scare you to death. I think you need to sit down and talk with a human being who has training in the whole genetics picture." —Anonymous

DTC genetic tests differ—and so can their findings

A few years ago, Francis Collins, the geneticist who headed the Human Genome Project, asked three different DTC gene-testing companies to examine his genome for mutations. (He used an assumed name to preclude any preferential treatment.) The three tests differed in cost and in the range of genetic variants tested for. While the three companies agreed on most results, each came back with a different assessment of Collins's risk for developing prostate cancer: One said lower-than-average, another said slightly elevated, and the third said 40 percent higher than the average male.

"There's a really important lesson here—the field is moving so quickly that any genetic risk predictions based on today's understanding will need to be revised in the context of new discoveries tomorrow. That applies not just to prostate cancer but to all of the rest of my risk predictions—what is possible now is only a blurry picture of reality." —Francis Collins

Are you ready to decide again about whether you would want to get a DTC genetic test for variants commonly linked to particular disease and non-disease traits?

Remember, there are no right or wrong answers, and only your choice will be recorded, not your name or any other identifying information.

Knowing all of the above, would you get tested?



A note of caution: With each passing month, DTC genetic tests, as opposed to specialized genetic testing ordered by your doctor, continue to improve in accuracy and sophistication, and their costs are dropping. Some experts predict that within a few years you will be able to get your entire genome scanned—all three billion base pairs of it—for as little as $1,000. However, it's one thing to scan a genome, another thing to accurately and usefully interpret the resulting information. Companies offering tests differ in their reliability, and you should research them thoroughly before deciding which to go with. And if you do get tested now, consider getting retested in a few years, because geneticists are constantly finding new genetic variants as well as suspected or actual links between them and various diseases and other conditions. For more information on genetic testing, see Sources.

facts & figures

Genetic tests, which are typically done on a sample of blood, saliva, hair, cheek cells, or other tissue, can identify permanent genetic variations that are associated with certain inherited disorders.

DTC genetic tests can identify traits, such as baldness or the ability to taste bitter; predicted response to drugs, from caffeine to blood thinners; and clues to ancestral origin. They can also determine risk factors for dozens of health conditions, from restless legs syndrome to breast cancer. But as noted earlier, such tests only look at a limited range of risk factors; for more comprehensive testing for diseases such as breast cancer, you should consult your doctor.

Most diseases, including Type 2 (adult-onset) diabetes and Alzheimer's disease, involve the interaction of multiple genes with the environment. Testing in most of these cases can only determine whether a person has a mutation in one of many genes (many more of which are not yet known) that contribute to a disease, and thus only whether that person has an increased risk of developing the disease.

DTC genetic tests range in price from under $100 to several thousand dollars, depending on the company and the type and complexity of the test.

Sources

General

Collins, Francis S. 2010. The Language of Life: DNA and the Revolution in Personalized Medicine. HarperCollins.

Davies, Kevin. 2010. The $1,000 Genome: The Revolution in DNA Sequencing and the New Era of Personalized Medicine. Free Press.

Elton, Catherine. 2009. "The Burden of Knowing." Boston Magazine. January.

Green, Ronald M. 2007. Babies by Design: The Ethics of Genetic Choice. Yale University Press.

Harmon, Amy. 2006. "Couples cull embryos to halt heritage of cancer." The New York Times, 3 September.

Zallen, Doris Teichler. 2008. To Test or Not to Test: A Guide to Genetic Screening and Risk. Rutgers University Press.

Scenario 4: Getting a Direct-to-Consumer Genetic Test

"I'm glad I took the tests…." Dickinson, Boonsri. 2008. "How much can you learn from a home DNA test?" Discover Magazine, 20 August. www.discovermagazine.com/2008/sep/20-how-much-can-you-learn-from-a-home-dna-test

"You know, I almost feel better…" Zallen (see General sources), 94.

"Finally we found a lab…" Ibid., 143.

"The Internet is wonderful…" Ibid., 144.

"There's a really important lesson here…" Collins (see General sources), xxii.

Credits

The author would like to thank Doris Teichler Zallen, author of To Test or Not to Test (see Sources, General), for reviewing this feature for accuracy and for her kind permission to quote extensively from her book. Thanks also to Lars Bertram, M.D., Head of the Neuropsychiatric Genetics Group at the Max-Planck Institute for Molecular Genetics; Mary-Claire King, M.D., Ph.D., at the University of Washington School of Medicine; and Mark Hughes, M.D., Ph.D., Senior Scientist and Director at the Genesis Genetics Institute. Thanks, finally, to Mary Crowley and Josephine Johnston of the Hastings Center (www.thehastingscenter.org) for helpful comments on the text.

Producer:
Peter Tyson
Designer:
Kim Ducharme
Developer:
Daniel Hart

Images

Intro: hand with pen over DNA sequencing
Jacob Halaska/Photolibrary/Getty Images
Page 1: IVF embryo testing
Pascal Goetgheluck/Photo Researchers, Inc.
Page 2: scans of normal (right) and Alzheimer's brains
Science Source/Photo Researchers/Getty Images
Page 3: woman crossing her arms
Helen McArdle/Photo Researchers, Inc.
Page 4: close-up of DNA sequencing gel
Steven Puetzer/Photographer's Choice RF/Getty Images