Genetic Testing: Look Before You Leap
Genetic testing can give you valuable and even life-saving information. But it can also alter your relationships with family members, complicate your insurance and employment status, and confront you with tough, perhaps unanswerable, questions. We hear more about the link between genes and disease everyday. If there is evidence of an inherited condition in your ]]>family history]]>, a genetic test may be able to provide you with valuable information. The tests can provide information on your own risk, or your child's risk, for an illness.
There are only a few inherited disorders that can give you a simple yes or no test. The more common test result is an estimate of your risk for developing a disease. The results and the options open to you after your test will vary depending on the particular condition for which you are tested. So take heed before you lift the veil from your genetic profile.
Beyond the Results
Results aside, other issues that may come up concerning genetic testing include:
- How long it takes to get the test results (if you are already pregnant this can be a real nail biter)
- The need to test other family members
- The current status of treatment for a condition
- The prospects for improved treatment
- The cost of testing
- Your age and circumstances
- What choices you will have once you have your results
And it doesn't stop there. The impact of genetic testing on your life can be like giving a good twist to a kaleidoscope—mostly the same pieces, but what a different image! And once you twist that kaleidoscope, there's no going back to the previous view.
Find a Guide
If you are considering having a genetic test, consult with a genetic counselor first. These specially-trained, certified health professionals can guide you through the numerous decisions, interpretations, and options of genetic testing. Most hospitals have certified genetic counselors on staff or you can contact the National Society of Genetic Counselors to find a board-certified counselor in your area.
To Test or Not to Test
The first question a genetic counselor can help you with is whether or not to have the test. Karen Johnson, a genetic counselor at Johns Hopkins University, specializes in counseling people who have cancer in their families. Her clients often come to her because of something they read, a family member was recently diagnosed, or because their doctor suggested it. Whatever their reasons for considering a genetic test, Johnson says, "More than half of the people I counsel decide not to have the test, depending on the condition in question. Often," she adds, "many people have overestimated their risk, and after counseling, better understand what their risk actually is and what options they have."
There are several scenarios in which genetic testing may be considered appropriate:
- Those who think they might have a birth defect, or might have or develop a genetic disorder
- Women who are pregnant after age 34
- Couples who already have a child with a genetic disorder, mental retardation, or a birth defect
- Women who have had two or more miscarriages or whose babies died in infancy
- Couples who would like testing or information about genetic disorders that occur frequently in their ethnic group
- Couples who are first cousins or other blood relatives
Deciphering the Results
If you decide to go ahead with the test, a counselor can help you interpret the results and define your options. In some cases, testing positive for a genetic mutation associated with a disease can mean you are virtually certain to develop the disease. In other cases, it may mean only that you might develop the condition. Depending on the disease, there are wide variations in treatments and preventive measures available.
Negative results are no less complex. Johnson did a study that found many people who tested negative for an inherited form of colon cancer stopped being screened for the disease altogether. Johnson says, "It appears that at least some of them misinterpreted the 'negative' results to mean they had no risk for colon cancer. What the test results actually meant was that they had little or no risk for the particular form of colon cancer associated with the particular genetic mutation we tested for."
Genetic testing doesn't affect just you. By definition, this is about families. At the minimum, you will need to provide a detailed and complete medical history of your family. Other family members may need to be tested as well. This is called a linkage test and is used when there is no direct test for a condition. Linkage tests use genetic information from other family members to better identify the genetic marker for a condition. Which, and how many, of your relatives will need to be tested depends on the condition and what its inheritance pattern is. Still other relatives may become involved as you may have to decide whether or not to tell them they are at risk for the illness. Who else will know—and what will they do?
Points to Ponder
Even now, in its infancy, genetic testing has great power for revealing information that can change the lives of individuals, families, and entire societies. Like many other new technologies, genetic testing provides ethical, social, and legal questions about how to balance an individual's right to privacy against society's need to protect itself. Other controversies surrounding genetic testing include sex selection, presymptomatic testing of children, and whether or not to warn third parties or to re-contact patients when new information on their genetic status becomes available.
There is no doubt that for some people genetic testing can be beneficial. But in this "information age," the effects of unintended consequences require as much consideration as do the potential benefits.
March of Dimes Foundation
National Society of Genetic Counselors, Inc.
A World of Genetics Societies
The Society of Obstetricians and Gynaecologists of Canada
Harrison’s Principles of Internal Medicine. 16th ed. McGraw Hill; 2005.
Weitzel, J. The current, social political, and medical role of genetic testing in familial breast and ovarian carcinomas. Curr Opinions in Obstet Gynecol. 1999;11:65-70.
Last reviewed March 2010 by ]]>Brian Randall, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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