Gene test -- then what?
Wandering the virtual aisles of a genetic-test website can be as dazzling and chaotic as shopping at a big-box hardware store on Saturday afternoon. Shelves are bursting with innovative products that promise to reveal a patient’s genetic propensity to conditions as varied as diabetes, alcoholism, post-traumatic stress disorder, Alzheimer’s disease and lung cancer. Fueled by the galloping pace of genomic research, new tests are being stocked daily.
Thinking about shoring up your personal health future? The signs say these are the tools you’ll need.
But don’t count on finding an employee to help you figure out how to use these intriguing new products, what to make of their results or whether you should have them to begin with. This is largely a DIY marketplace, and patients intent on detecting cracks and flaws in their personal genetic foundation and acting to patch them up are finding they’re pretty much on their own.
That’s the finding of a new study by researchers at the Rand Corp. and the Veterans Administration, published as the centerpiece of a special edition of the Journal of the American Medical Assn. devoted to genomics and genetic testing. After reviewing the findings of 68 studies on genetic testing -- its practice, its meaning as understood by healthcare professionals and patients, and its effect -- the authors concluded that a “wide gap” exists “between what knowledge is available and what health systems need to know” if genetic testing is to improve the nation’s health.
“This is such an exciting time right now,” said Dr. Maren Scheuner, an internal and genetic medicine specialist and lead author of the JAMA article, “Delivery of Genomic Medicine for Common Chronic Adult Diseases.” But, she added, “lots of different things will need to change as we adopt this new information and technology.”
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Detailed advice lacking
Today, genetic tests can identify and characterize 1,550 genes linked to health outcomes -- a more than 15-fold increase in the last 15 years. As the 20th century came to a close, genetic tests were in wide use to identify carriers of single-gene mutations -- patients who, as a result, had a greatly increased likelihood of developing devastating diseases such as sickle-cell anemia or Huntington’s disease. Among the best known and most widely used are those that test for the BRCA1 and BRCA 2 genetic mutations, which raise a woman’s risk of developing breast and/or ovarian cancer to as high as 80%.
Many of the new assays, however, reveal health prospects more subtle and complex. They can ferret out the genes -- in some cases, whole suites of genes that interact with each other and the environment -- that raise a patient’s risk of developing chronic disorders such as depression, diabetes, osteoporosis, cardiovascular disease and some cancers. But how they interact with each other and the environment, and how powerfully or marginally each of many genes contributes to a patient’s increased disease risk, is poorly understood.
For patients, a finding of increased genetic risk for these chronic conditions could have the positive effect of encouraging lifestyle choices aimed at prevention. But genomic research remains short on specific advice that physicians could use to motivate patients, such as how much maintaining a healthy weight or a regular schedule of exercise could counteract the risk increase from a given genetic mutation.
As a result, a patient deliberating whether to get tested for these gene variations is likely to do so amid huge uncertainty. Researchers and scientists are still working to unlock these mysteries. In studies and surveys assessed by Scheuner and her colleagues, majorities of physicians acknowledged they feel poorly equipped to advise patients on whether to get these tests -- or, if they do, how to interpret their meaning. Medical geneticists and genetic counselors -- all but 7% of whom are clustered in pediatric and obstetric specialties -- are scarce and poorly trained in chronic disease and adult medicine. Insurance companies have no means of assessing the therapeutic value of the tests and therefore are disinclined to pay for them.
And patients, though excited by the promise of the new genomic medicine, worry that the results of genetic tests, when they suggest a heightened risk of disease, could be used against them by insurance companies, employers and even marital prospects. In studies reviewed by Scheuner, 30% to 50% of patients surveyed said concerns about privacy and insurance coverage would influence their decision about undergoing gene testing.
Finally, researchers acknowledge that there’s substantial uncertainty about the effect genetic tests will have on patients. Amid abundant evidence that obesity and sedentary lifestyle contribute strongly to chronic diseases, large numbers of Americans remain overweight and don’t exercise.
Whether a finding of increased genetic risk will prompt a patient to take action is equally uncertain, Scheuner said. One study in which overweight patients got dietary recommendations informed by genetic tests found improved weight loss compared with those who did not. But a 2002 study of longtime smokers found that those who received a positive finding for increased genetic risk of lung cancer were no more likely to stop smoking than were those whose genetic test found no such genetic predisposition.
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Thriving market for tests
But ready or not, said UCLA cancer and genetic specialist Dr. Patricia Ganz, the age of genomic medicine is on its way. Scientists are finding significant associations between genes and diseases, and those are quickly finding their way into a thriving market for medical screening. Physicians and genetic counselors, Ganz said, will need to be trained in greater numbers to prepare for the increased use of such tests. And, he added, federal legislation -- such as a bill passed by the House but now stalled in the Senate -- will be needed to protect patients from genetic discrimination.
“We’re going to have people who are willing to pay for genetic tests -- we know that because they already pay for full-body CT scans,” Ganz said. “They’ll have this done and no one will know how to present this information. That’s the thing we really need to guard against.”
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