What should primary care physicians keep in mind about genetic testing?

Genetic testing has made the world of the family physician much more complicated and controversial. You should expect greater demands from your patients for genetic testing, especially as more tests for diseases become available through the mail or Internet.

As the primary care provider (and if genetic counselors and medical geneticists are not readily available), you and your patient(s) should go though an information gathering phase. This will help you and your patient ascertain whether genetic testing is necessary and/or advisable. In addition, when genetic counselors or medical geneticists are consulted, the information you have collected from your patient will be very important.

Below are some general things to keep in mind:

  • Genetic testing is complex, and communication of risks and uncertainties must be attended to thoughtfully and critically. Consumers and healthcare professionals need to know that genetic information can have profound side effects i.e., possible insurance consequences, work discrimination, psychological side effects such as people’s perceptions of their body, family, and future. (from GDP transcript)
  • Genetic tests are quite variable. Some tests are quite clear cut and predictive and other aren’t at all. (GDP)
  • Genetic tests provide information about family members and relatives. Disclosure of family information can often be helpful to family members but also can lead to breaches of confidentiality that must be considered and addressed proactively. Health care professionals have a duty to warn. In other words, privacy regulations underscore the provider’s obligation to maintain the confidentiality of medical information. However, if the information represents a significant, imminent and remediable threat to another person’s health, the provider may need to consider whether s/he has a duty to contact the person (or in the case of a minor, the minor’s guardian or legal representative, in the absence of explicit permission.
  • Health care providers need to provide opportunities for their patients to express their reasoning and associated emotions in regards to testing. The most important goals of the counseling discussion is to ensure that patients have considered all aspects of the testing opportunity to his/her satisfaction in making this decision.
  • All diagnoses carry with them other social, cultural and psychological meanings as filtered through the patient’s viewpoint and health model. The physician must simultaneously assess the medical information to be conveyed, the patient’s baseline perspective and comprehension of the new information, the psychosocial implications of the diagnosis for the patient, and the support systems the patient has. A strong-patient doctor relationship can help the patient gain a perspective on his/her disease.

Urban legends and genetic testing

I heard a news item on the Today show, which suggested that a group of workers are being forced to take a DNA test so that a prankster at a hotel can be identified. After trying to track this down, I suspect it is another of the urban legends related to human body products and food contamination. Odd that it would be aired on Today--and not findable in searches of the MSNBC website.

This--and an e-mail I received on ovarian cancer--sent me to a website I had not explored before. This site, and a number of others apparently, tracks stories known as urban legends. these stories are intended to evoke emotion and they generate their own following, when the stories are passed along from one person to another.

I searched the site (http://www.snopes.com/) for genetic testing, genetic, and DNA and found a surprisingly low number of items. The only one of interest to human genetic testing relates to paternity testing. Recently, some newspapers suggested that as many as 30% of all fathers are raising children not their own. This urban legend is somewhat tricky because it involves statistics--that stuff so many of us don't understand.

First, the real percentage is closer to 1%--not 30%, so don't run out and get a DNA test for your children and yourself. Second, the fallacy of the numbers lies in the same selective population used in forensic testing. When the only people tested are those under "suspicion", the numerical "proof" of paternity or guilt is much greater than when the general population is tested. If 2 or 3 people are tested, and there's a DNA match between the children (or the victim) and one of the two or three people, this is often considered proof. If 1 million people were tested, the proof would be less sure.

So, don't believe everything you hear or read. It may be an urban legend, in which case you can check Internet sites to see if it turns up. Or, it may be that only a few people were tested. Or--it could be true! Whatever the situation, have fun with the story, but investigate deeper before you make any life-changing decisions. 

 Marie Godfrey, PhD