Behavior and Associated Actions with a Commercial Genetic Test


Synopsis: Few patients undergoing genetic testings for familial adenomatous polyposis received genetic counseling or gave written informed consent.

Source: Giardiello FM, et al. N Engl J Med 1997;336: 823-827.

The discovery of numerous genetic mutations associated with a variety of common cancers has led to vigorous debate about their appropriate use, interpretation, and ethical and insurance consequences. One of the first commercially available genetic tests was for the adenomatous polyposis coli (APC) gene defect on the long arm of chromosome 5. The disorder is inherited as autosomal dominant disease and is associated with the development of numerous colorectal adenomas in young adulthood and a progressive increasing risk of colorectal cancer. The test became commercially available in 1994. Giardiello and colleagues from John Hopkins identified all tested patients across the country in calendar year 1995 and collected data by telephone interview of their physicians and abstracting the medical records. The results for the 177 patients tested are as follows:

Appropriate indication for test 83%

Genetic counseling before testing 19%

Written informed consent 17%

Correctly interpreted test results 69%


Despite strong statements from the National Institutes of Health, the American Society of Human Genetics, and the American Society of Clinical Oncology about the importance of genetic counseling and informed consent, neither was done in more than 80% of cases. As a generalization, interpretation of genetic testing is not a simple "Yes—you’re doomed/no—you’re fine" situation but a classic Bayesian pre-test/post-test probability event. I believe this study supports the position that genetic tests should only be requested by genetic counselors. In addition, managed care plans that limit access to genetic counselors are being fiscally and ethically irresponsible.