 January 2003 • Volume 9 • Number 1 |
 Genetic profiling: Marketing DNA tests directly to patients is gaining popularity. But some physicians question the practice, fearing what patients may -- or may not -- do with the results. Here's an example of what a patient who's submitted a self-obtained DNA sample for analysis might expect to receive via return mail. |
It's hard not to get caught up in the drama inherent in unraveling the mysteries of the human genome. The stakes are high: At issue is the hope that someday the information gleaned from those twisting tendrils of DNA will allow us not only to cure debilitating health problems but also to prevent them.
Given that hope, having the chance to glimpse our so-called health future may be difficult to refuse.
And although each day seems to bring another revelation about the origins of many hereditary illnesses -- perhaps triggering development of some new means of gauging individual risk for those ailments -- it doesn't necessarily follow that pursuing such testing is the best course.
Sometimes, says AAFP Past President Richard Roberts, M.D., J.D., of Madison, Wis., the adage "knowledge is power" doesn't apply. No matter how well-informed a patient may wish to be, if nothing stands to be gained by testing, what's the point?
"We Americans cling to a belief that knowing more is doing better. Unfortunately, this is not always the case," says Roberts, who often has been AAFP's spokesperson on genetic issues.
"Regarding genetic testing, there are very few conditions that are driven exclusively by our genetics -- much of their adverse outcomes also are driven by our environment and our behaviors," he says. "As an example, we know that alcoholism represents a genetic susceptibility. Yet if we never use alcohol, we don't fall victim to the disease."
Passing the "screening" test
Three components are required to ensure the usefulness of any screening test, according to Roberts. They are evidence that:
"This is something we regularly deal with already," Roberts says, citing a common example: A man goes to a hospital-sponsored health fair and receives a prostate-specific antigen assay for prostate cancer. He brings the full report to the office, demanding to know what it all means and what you plan to do about it.
"You go back to the beginning and ask the man what he wants," Roberts says. He cites a Sept. 12, 2002, New England Journal of Medicine report on a Swedish study that showed surgery for early-stage prostate cancer resulted in a reduced risk for death from prostate cancer but no change in overall death risk. "Men interested in such surgery need to balance that against the impotence and incontinence that are likely to result from the procedure," he says.
The same goes for genetic testing. The expectations it creates for patients, whether negative or positive, can be psychologically damaging, says Roberts.
"I am reminded that the genetic code consists of four letters representing the main building blocks of DNA: A (adenine), C (cytosine), G (guanine) and T (thymine)," he says. "Many believe that genetic testing, given its current state of development and lack of proof of improving health outcomes, also consists of four letters: H-Y-P-E."
"Genetically Customized" Results
Part of the lure of self-administered genetic tests may have to do with the ease of at-home collection of a reasonably reliable DNA specimen, says Louise Acheson, M.D., associate professor of family medicine and assistant professor of reproductive biology at Case Western Reserve University, Cleveland, Ohio. Acheson has done work on the application of new genetic knowledge to clinical practice.
"Taking a specimen for DNA testing is very easy," Acheson notes. "A swab of cells from inside the mouth or a blood sample that contains white blood cells is all you need for getting DNA from that person. So it's technically feasible -- and very easy -- for a patient to take a buccal swab at home. That DNA can then be analyzed for various genetic markers."
For example, United Kingdom-based Sciona says it "tests for common variations in genes which affect your individual response to medicines, food and the environment."
Using a simple cheek swab and a completed lifestyle questionnaire, Sciona's "team of geneticists, molecular biologists, medical doctors and dieticians" evaluates the person's genetic risk for chronic illnesses such as osteoporosis or cardiovascular disease and devises a tailored dietary regimen and lifestyle advice intended to minimize or eliminate that risk.
Cost? About $175.
Closer to home, GeneLink of Margate, N.J., sells a test that analyzes several genes linked to cancer and eye disease, among other ailments. GeneLink made strategic alliances this past spring with Berwyn, Pa.-based NuGenix and Garden State Nutritionals of West Caldwell, N.J. Purchasers of the GeneLink test receive "genetically customized" nutritional supplements -- personalized vitamin pills -- along with their genetic report. All for about $200.
"Can" versus "should"
But again, just because you can doesn't mean you should: Although this sort of testing may be feasible, says Acheson, taking the time to properly counsel patients about genetic testing -- especially when they trundle into the office with test results they may have obtained elsewhere -- simply isn't always possible during the average primary care visit. "It's not feasible with the time of the visit that we usually have with our patients," says Acheson.
Furthermore, knowledge about genetic issues is growing by leaps and bounds. Practicing physicians can have difficulty keeping up. That's why Acheson says comprehensive genetic counseling is often best left to health professionals with specialized education, training and experience in medical genetics and counseling. For more information about these professionals, visit the National Society of Genetic Counselors Web site at http://www.nsgc.org/.
Of course, in the real world, patients ask their family doctors about this stuff, right? Right.
Here's how Roberts suggests responding when patients come to the office with results from a self-administered DNA test:
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