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Genetic Testing Dilemmas

  • By Peter Tyson
  • Posted 03.08.12
  • NOVA

Scenario 2: Alzheimer's Disease

Several members of your family have developed Alzheimer's disease late in life. You're thinking about getting tested for the genetic factors that scientists have identified as raising a person's chances of developing the disease later in life. There is currently no cure or treatment for Alzheimer's, nor is there convincing evidence that medication or diet will delay or prevent its onset in a susceptible individual.

PET scans of normal and Alzheimer's brains

Given the above information, would you get tested?

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:

some wonder why learn their risk if no treatment or cure

Because there is little you can do if you have, say, one or two copies of the e4 allele and thus an increased risk of Alzheimer's, some people feel why get tested for such mutations?:

"[M]y father was diagnosed with Alzheimer's. …[T]he reason I didn't pursue genetic testing for Alzheimer's was because if I had it identified, there really isn't any cure for it. At this stage in my life, I didn't want to know that at some point I was going to encounter it. There really isn't any treatment. … So, why make your life more depressing?" —Anonymous

some want a chance to prepare

Others believe knowing about an increased risk would at least give them and their loved ones a better opportunity to ready themselves for it should it occur:

"I talked with my doctor about getting a genetic test, and he wasn't keen on it. His comment was, 'Well, what would you do?' And I said, 'Plan.' … It would prompt me to make plans to do a lot of things through my sixties and seventies if I am in good health." —Anonymous

you could contribute to research

Some people feel that if they were found to have a higher risk for Alzheimer's that they would help with studies into the disease:

"I think I would become more active in Alzheimer's research. …[I]f… I knew I was more likely to get it, I would go ahead and do that [to help in] detecting it early and finding better ways to measure what is happening." —Anonymous subject with Alzheimer's among immediate family members

some would rather leave everything to fate

Others would prefer not to test and let fate take its course:

"My uncle died of Alzheimer's, and I think he was like eighty-something, and my mother who is eighty-five has it… So, I am looking at the fact if it does hit me I am looking at being about the age of my mother. I leave my life up to God. And He has His plans for me, and if I get struck down with the disease so be it. I will just have to do the best I can with it and my husband will do the best he can with it too." —Anonymous

some fear genetic discrimination

Some decide not to get tested for fear that health insurers or employers could discriminate against them if they learned that those individuals had a higher risk for Alzheimer's*:

"I talked to my internist about it, and at the time he was telling me that there was testing that could be done but it's one of those things that is two-sided because one thing, you could find out nothing definite—that you were predisposed I guess for getting Alzheimer's—and the other thing is it would be like a preexisting condition for insurance purposes. I guess I just decided not to go any further with it." —Anonymous

*Editor's note: The 2008 Genetic Information Nondiscrimination Act, or GINA, protects individuals against discrimination in health coverage and employment on the basis of genetic information, but it does not extend to life, disability, or long-term care insurance.

Are you ready to decide again about whether you would want to get tested for genetic markers that indicate an increased risk for getting Alzheimer's?

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?

facts & figures

Alzheimer's is a degenerative disease of the brain that causes dementia, including gradual loss of memory, judgment, and ability to function.

Affecting nearly five million Americans alone, it usually occurs in people older than age 65. This is called late-onset Alzheimer's (early-onset Alzheimer's represents only 5 percent of cases).

The causes of late-onset Alzheimer's remain unclear, but experts believe it is related to a complex mix of variations in multiple genes in combination with influences from an individual's environment.

Scientists have identified a variant in the APOE gene known as the e4 allele that is a risk factor for Alzheimer's disease. Carrying the e4 allele can increase the risk of developing Alzheimer's by up to 15-fold compared to non-carriers of this variant. At the same time, not all people with Alzheimer's have the e4 variant, and not all people with the variant will get the disease.

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 2: Alzheimer's Disease

"[M]y father was diagnosed…" Zallen (see General sources), 73.

"I talked with my doctor…" Ibid., 91.

"I think I would become more active…" Ibid., 101.

"My uncle died of Alzheimer's…" Ibid., 25.

"I talked to my internist about it…" Ibid., 103.

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