Multiplex Genetic Testing
Among the most significant advances in the development of genetic medicine is the ability to test for genetic origins of specific conditions. In previous reports, the American Medical Association's Council on Ethical and Judicial Affairs has addressed many ethical issues associated with the application of the growing body of genetic information and accompanying technologies.
Here, analysis is offered regarding testing for multiple genetic conditions simultaneously, or "multiplex genetic testing."
The term multiplex genetic testing can mean different things. It commonly refers to testing for multiple mutations that give rise to a single disorder, such as cystic fibrosis or phenylketonuria. This report deals instead with multiplex genetic testing where tests for completely different conditions are offered in a single session. As the mapping of the human genome progresses and tests for newly discovered genes are developed, the possibility has arisen that many different testing "packages" could be administered simultaneously. This latter kind of multiplex testing creates a new level of complexity because the modes of heredity, social implications, and availability of treatment can differ greatly among the conditions tested.
Existing tests can be divided into three broad categories: first, tests can be performed to find genetic conditions that will lead to future inevitable disease onset as in the case of Huntington disease. Second, tests can be designed to find specific genetic information that indicates a heightened risk to possible disease onset. Often referred to as "susceptibility testing," this type of test can be used to provide information about the possibility of contracting specific cancers, such as colon or breast cancer. Finally, genetic tests can be used to determine a patient's carrier status, providing information about the existence of a gene or gene mutation that is not necessarily manifested in an individual's phenotype, but that may be passed to children. The implications of the information conveyed by each test are different and are best addressed in separate ethical analyses.
The implications of genetic tests also differ depending on the population targeted for testing. For instance, genetic information provided to couples in the process of making reproductive decisions will likely have a different impact from information provided to an individual who has no intentions of having children. Similarly, providing genetic tests to children at the request of their parents may have different ramifications from providing the same tests to consenting adults. These differences are crucial to any analysis of genetic testing and must be given careful consideration as the availability of genetic medicine continues to grow.
Multiplex testing may compound the ethical complexities associated with single genetic tests rather than simply combining them. It should not be concluded that safeguards designed to limit the ethical risks associated with single genetic tests will be sufficient to meet the challenges that arise when tests are offered in combination. While this may be true in limited circumstances, in general the clinical application of multiplex testing should not proceed without a careful examination of the associated regulatory and ethical issues. Marketing of multiplex testing, both directly to consumers and through physicians' offices, could provide appealing financial returns to the biotechnology industry as well as to genetic testing centers. In the face of these incentives encouraging rapid development and distribution of multiplex tests, it is critical to confront the relevant ethical issues before these tests are widely conducted without necessary safeguards. As a response to this need and as a part of its continued efforts to address the ethical implications of genetic medicine, the Council presents the following analysis of multiplex genetic testing. …