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Genetic testing for bipolar disorder
A positive response to hypothetical questions
  
By
Edward R. Winstead


Surveys that ask hypothetical questions about medical tests are not commonly found in scientific journals. But genetic testing is such a thorny issue that opinion polls about these tests can be informative. Especially, perhaps, when it comes to mental illness.


A few years ago researchers at Johns Hopkins University School of Medicine conducted a pilot study on the attitudes of people with bipolar disorder and their spouses about genetic testing. The survey, which was published in the American Journal of Psychiatry, explored social and ethical issues related to gene tests, including prenatal testing, abortion and testing minors.

The researchers found that participants in the survey were quite positive about genetic testing for bipolar disorder. The vast majority indicated that the benefits of knowing whether they or their spouses carried a gene for bipolar disorder outweigh the risks.

Most respondents said that a positive test result for a gene linked to bipolar disorder would not have deterred them from marriage or childbearing. A decisive majority of bipolar patients and spouses said that they would not choose to abort a fetus with a gene for bipolar disorder. Furthermore, a majority of patients and spouses favored testing minors for the gene.

The study's lead author Carol Lynn Trippitelli discussed the survey last week at the annual Mood Disorders Symposium held at Johns Hopkins. She emphasized that the questions are hypothetical because a gene test for bipolar disorder does not exist. Many studies have indicated that genetics plays a role in the onset of bipolar disorder, also known as manic depression, but no specific genes have been identified.

The researchers drew no broad conclusions from the pilot study. The survey included only 45 couples who by and large were well educated about the genetics of bipolar disorder—perhaps more so than in the general population.

Anticipating the needs of patients and their families for genetic testing can be tricky, Trippitelli noted at the symposium. Before a test was available for Huntington's disease, surveys indicated that demand for genetic testing would be high, but demand has been relatively low. Huntington's is a degenerative brain disorder linked to a single gene.

People may not want the Huntington's test because the disease onsets late in life and has no cure. By contrast, Trippitelli pointed out, bipolar disorder tends to onset earlier in life and effective treatments are available. For these reasons, she said demand for genetic testing in families with a history of the disease could be relatively high.

Another author of the study is Kay Redfield Jamison, who described her own experience with bipolar disorder in An Unquiet Mind: A Memoir of Moods and Madness (1997, Random House). She often presents research on mood disorders in historical figures at the Hopkins symposium. This year's subject was "The Life and Death of Meriwether Lewis."

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Trippitelli C.L. et al. Pilot study on patients' and spouses' attitudes toward potential genetic testing for bipolar disorder. Am J Psychiatry 7, 889-904 (July 1998).
 

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