Genetic Testing Health Article

Risks

Collection of amniotic fluid and chorionic villi sampling, have the risk of miscarriage, infection, and bleeding; the risks are higher for the chorionic villi sampling. Because of the potential risks for miscarriage, 0.5% following the amniocentesis and 1% following the chorionic villi sampling procedure, both of these prenatal tests are offered to couples, but not required. A woman should tell her physician immediately if she has cramping, bleeding, fluid loss, an increased temperature, or a change in the baby's movement following either of these procedures.

After bone marrow collection, the puncture site may become tender and the person's temperature may rise. These are signs of a possible infection.

Genetic testing involves other nonphysical risks. Many people fear the possible loss of privacy about personal health information. Results of genetic tests may be reported to insurance companies and affect a person's insurability. Some people pay out-of-pocket for genetic tests to avoid this possibility. Laws have been proposed to deal with this problem. Other family members may be affected by the results of a person's genetic test. Privacy of the person tested and the family members affected is a consideration when deciding to have a test and to share the results.

A positive result carries a psychological burden, especially if the test indicates the person will develop a disease, such as Huntington's chorea. The news that a person may be susceptible to a specific kind of cancer, while it may encourage positive preventive measures, may also negatively shadow many decisions and activities.

A genetic test result may also be inconclusive meaning no definitive result can be given to the individual or family. This may cause the individual to feel more anxious and frustrated and experience psychological difficulties.

Prior to undergoing genetic testing, individuals need to learn from the genetic counselor the likelihood that the test could miss a mutation or abnormality.

Normal results

A normal result for chromosome analysis is 46, XX or 46, XY. This means there are 46 chromosomes (including two X chromosomes for a female or one X and one Y for a male) with no structural abnormalities. A normal result for a direct DNA mutation analysis or linkage study is no gene mutation found.

There can be some benefits from genetic testing when the individual tested is not found to carry a genetic mutation. Those who learn with great certainty they are no longer at risk for a genetic disease, may choose not to undergo prophylactic therapies and may feel less anxious and relieved.

Abnormal results

An abnormal chromosome analysis report will include the total number of chromosomes and will identify the abnormality found. Tests for gene mutations will report the mutations found.

There are many ethical issues to consider with an abnormal prenatal test result. Many of the diseases tested for during a pregnancy, cannot be treated or cured. In addition, some diseases tested for during pregnancy, may have a late-onset of symptoms or have minimal effects on the affected individual.

Before making decisions based on an abnormal test result, the person should meet again with a genetic counselor to fully understand the meaning of the results, learn what options are available based on the test result, and what are the risks and benefits of each of those options.

BOOKS

Berg, Paul, and Maxine Singer. Dealing with Genes: The Language of Heredity. Mill Valley, CA: University Science Books, 1992.

Farkas, Daniel H. DNA Simplified: The Hitchhiker's Guide to DNA. Washington, DC: American Association of Clinical Chemistry Press, 1996.

Gelehrter, Thomas D., Francis S. Collins, and David Ginsburg. Principles of Medical Genetics. 2nd ed. Baltimore: Williams and Wilkins, 1998.

Grody, Wayne W., and Walter W. Noll. "Molecular Diagnosis of Genetic Diseases." In Clinical Diagnosis and Management by Laboratory Methods, edited by John B. Henry. 19th ed. Philadelphia: W. B. Saunders Company, 1996, pp. 1374-1389.

Holtzman, Neil A., and Michael S. Watson, eds. Promoting Safe and Effective Genetic Testing in the United States. Final Report of the Task Force on Genetic Testing. National Institutes of Health-Department of Energy Working Group on Ethical, Legal, and Social Implications of Human Genome Research, 1997.

Motulsky, Arno G., Richard A. King, and Jerome I. Rotter. The Genetic Basis of Common Diseases. New York: Oxford University Press, 1992.

Mueller, Robert F., and Ian D. Young. Emery's Elements of Medical Genetics. 9th ed. New York and Edinburgh: Churchill Livingstone, 1995.

Watson, James D. The Double Helix. New York: Atheneum, 1968.