I have asked one of my students who is acting as a Teaching Assistant for a new course on personalized genomics at Stanford to comment on the recent Government Accounting Office testimony on Direct-to-Consumer Testing.
On July 22, 2010, the Government Accountability Office (GAO) released a testimony on Direct To Consumer (DTC) Genetic Testing companies. In the testimony, the GAO sent DNA from 5 anonymous donors to 4 anonymous DTC companies. At times, the results were astonishing, such as claims made by some of the companies taking advantage of ill-informed customers to sell custom supplements “based” on genetic test results. However, the testimony also revealed a fundamental disconnect in communication between science, medicine, and the public: a disconnect that has always existed, but is now being brought to the public eye, as recent technologies have begun to bridge the gap between scientists and consumers.
To preface, it is of course outrageous that anyone interpret a DTC genetic test as a diagnostic test (at least in their current form). Analysis of a personal genome is not a medical test. For the bulk of genetic markers, having a “high risk” allele for a disease is not even close to a diagnosis of the disease. It is simply an indicator that on average, in the particular population chosen by a research study (which are often small populations or populations selected to be enriched for a particular disease), individuals with that particular allele had a higher incidence of the disease in question than individuals without the allele (i.e. the “high risk” allele has a higher odds for the disease than the other). The companies then translate into a overall disease risk, which adjusts the prior probability of getting the disease by this odds ratio. Depending on which studies and genes/alleles a company takes into consideration, this risk may be vary considerably. In any case, the report provides a final probability of getting a disease, which may or may not actually be the same as the actual outcome. Just as an individual can get lung cancer without smoking, one can get diabetes even with a below average risk.
This is not to say all the calculations of the disease risk interpretations of all these companies are flawless (we haven’t verified the math and studies in all these companies), but the fact remains that there are legitimate scientific differences on how to interpret the data. While no particular method is outright “wrong,” there are better and worse ways to analyze results of genetic tests and competition among DTC companies for the highest quality interpretations should become increasingly important. Of course, it is objectively difficult to measure which interpretation is “best,” but this will change as more data become available both in predictive claims and possibilities for validation.
According to the testimony, the Department of Health and Human Services’ Secretary’s Advisory Committee on Genetics, Health, and Society notes that “[practitioners] cannot keep up with the pace of genetic tests and are not adequately prepared to use test information to treat patients appropriately.” While this may be true at present, this need not stop information from genetic tests from entering the clinic. A general practitioner may not be able to keep up with the latest advances in neurosurgery, but that’s where the specialist system thrives. In any case, just as clinicians are expected to demonstrate a basic level of competence in immunology in medical school, genetics must be treated the same way. Here at Stanford, a pilot project was launched to teach medical students about the field of genetic testing in an interactive classroom setting with state-of-the-art methods for analysis of personal genotypes.
Deceptive marketing, including “personalized supplements” (allegedly with celebrity endorsements) and drugs that may “repair damaged DNA” (allegedly called “epigenetics”), to say nothing of surreptitious testing and scientifically nonsensical claims, are inexcusable and irresponsible practices for any company, not limited to this particular market. However, the delicate matter of genetic testing and its use as a clinical guidance tool is a concept that must be explored further. The GAO uses the phrase “misleading test results”: it should be noted that while the current implementation of the reporting of test results may be in certain ways misleading, the framework of genetic testing is not in itself misleading. Proper interpretation is based in the same mathematical and biological context as much of today’s medicine. There is great potential for the use of genetic tests in the clinic, so long as results are carefully interpreted. While this was often limited to geneticists in the past, we hope that this can be soon accomplished by physicians and the public.