It’s only been within the past decade with the mapping of the human genome that genetic testing has shifted focus from family planning to prediction. For instance, a couple looking to start a family with a history of Huntington’s disease would test to ensure that they don’t pass the gene defect to their offspring. Compare that to the testing for BRCA-1 and 2 genes to predict the possibility of breast cancer in a mature adult.

       This type of predictive testing is novel, but not infallible. In fact, before spending time and money on genetic tests, we might first think about what we hope to learn, and how and by whom the results will be interpreted. We must also look at whether the clinical philosophy is prescriptive or part of the detective work.

       There is a natural curiosity about our genetic makeup that has to do with an emerging concept in the field of human genome mapping. Epigenomics proposes there are chemical compounds that can tell a
particular gene what to do; a gene mutation alone is not a predictor of disease. This puts a lot of the decision-making about lifestyle and personal choice back into the hands of the patient, regardless of the test result.

       On the other hand, gene mapping raises privacy concerns. It currently costs about $4,000 to map the human genome, making it a costly endeavor simply to learn that there is natural variation across a particular gene pool. Pharmaceutical companies—including Genentech and Pfizer—pay handsomely for access to these reports. The promise of the new field of pharmacogenomics, or personalized medicine, is better therapeutic decisions related to dosing; however, there is concern by some that centralized reporting will be made public.

       The criticism of genetic tests is well founded in part because the results produce a very complicated set of percentages that someone, preferably a doctor with no stake in the outcome, has to interpret. Even among practitioners that are comfortable ordering genetic tests, the data can be used to support a wide variety of practices and beliefs.

       As detective work, a negative result might indicate a risk factor, but only one of many that include all the other environmental influences that are external to gene expression. A genetic test could be used to detect a weakness in detoxification methods that contribute to poor lymphatic drainage which contribute to cancer, for instance. That said, much of the same information can be detected by a skilled clinician.

Dr. Doug Pucci, in Oradell, NJ, is the author of You Are Not Your Diagnosis. Connect at GetWell-Now.com and 201-261-5430.