As DNA testing technologies have gotten simpler and cheaper, home DNA testing kits have become increasingly popular. For a relatively small fee, consumers can mail in a sample of their saliva or a swab from their cheek for information about their ancestry. But many of these genetic tests also yield information about future health and disease risk, and that should be cause for concern, says Wayne Grody, MD, PhD, director of the UCLA Molecular Diagnostics Laboratory and Clinical Genomics Center.
Dr. Grody points out that much of the genetic information sought from such tests has no value to medical decision making. “You might learn that you have a 3 percent lifetime risk of Parkinson’s disease,” he says. “What are you supposed to do with that information? There is no way to prevent Parkinson’s. That percentage isn’t much higher than the risk for the general population. And we’re not entirely sure about the reliability of the genetic markers in predicting this disease.”
While geneticists have learned a great deal about the human genome in recent years, there is far more that is still not understood, Dr. Grody notes. Yet, too many home testing kits offer results stemming from variants in genes that are at the research stage. For example, results might suggest a moderately increased risk of heart disease and stroke based on genetic information that scientists view as far from predictive. “They’ll recommend that you eat more vegetables, which could apply to almost every adult in the United States,” Dr. Grody says. “You don’t need a DNA test to tell you that.”
In the case of genetic-testing results that are more definitive, such as those pointing to the risk of familial cancers or inherited neurological disorders, Dr. Grody is concerned that consumers will be ill equipped to handle troubling information without guidance of physicians or specially trained genetic counselors. “When you tell a woman she has an 85 percent lifetime risk of breast cancer, and she is sitting in her home with no options or knowledge about what she can do with that information, it is potentially very harmful,” he says.
Dr. Grody says that any genetic test that may suggest future implications on an individual’s disease risk should be preceded by counseling to explain its limitations and to determine whether the test is appropriate, as well as post-test counseling to put the results in perspective and refer the person to a specialist, if needed. UCLA’s genomics center has strict criteria before it begins offering a genetic test — ensuring both that the results will be scientifically reliable and that there is something that can be done for patients who receive concerning results. In addition to conducting single-gene tests, UCLA is among the only centers to offer a comprehensive analysis and diagnostic interpretation of an individual’s entire protein-encoding genome, involving more than 20,000 genes, to potentially locate a single DNA change responsible for rare disorders that in many cases have eluded diagnosis for years.
In some cases, Dr. Grody says, home DNA tests have provided important information that individuals have brought to the attention of their physician. But he is concerned that the potential harms of such tests outweigh the benefits. “Our genetics clinic gets an increasing number of calls from people who either don’t understand the results or are upset and seeking someone to explain the findings to them,” Dr. Grody says. “Just as we don’t want someone walking into a pharmacy and purchasing certain medications without a prescription, it makes sense that most of these DNA tests should be ordered by doctors.”