The science of unraveling the human genome has been on fast-forward during the last few years… leading to the premature development — and marketing — of a slew of direct-to-consumer (DTC) genetic tests. These may seem harmless… after all, what’s the risk in swabbing your cheek, sending the sample to a lab and learning how likely you are to develop heart disease? But this is very much a scenario of buyer beware.
The home test market is a relatively new and not so terrific twist on the evolving science of genetics. There are currently more than 1,000 genetic tests available and many more in development, but the science available right now is actually useful to only about 2% of the population, according to a report from a recent government panel called the Secretary’s Advisory Committee on Genetics, Health and Society. Of course that number will grow, but in the meantime, according to the report, much of what’s available is of dubious value and can, in fact, lead people to make unwise, perhaps even dangerous decisions based on data that is highly questionable.
The pitch to consumers sets you up to believe it’s almost as easy to learn your risk of developing cancer, heart disease or diabetes, among other things, as to subscribe to a new magazine — send in your credit card information and some sort of physiological sample to get information you can use to make important decisions about your future. The marketing is way ahead of the science, however. I called Gail Javitt, JD, MPH, who leads a genetic testing quality initiative at the Genetics and Public Policy Center at Johns Hopkins University to see what I could find out about direct-to-consumer genetic tests.
The government report called the industry that has grown around the science of human genetics “questionable.” Many tests are marketed with false, misleading or ambiguous claims. Often the people who analyze the results don’t have the qualifications to do so reliably. Plus, these tests, which can cost thousands of dollars, are also marketed with expensive and sometimes phony personalized supplement regimens to prevent the disease they ostensibly predict. Javitt told me that tests vary widely in quality, and at present there is a serious lack of adequate regulation and oversight. There are currently more than 1,000 genetic tests available, with new discoveries pointing the way to the potential for new ones popping up almost daily. There have been important and valuable innovations in the field of genetic testing, affirms Javitt, noting for instance that genetic tests for Huntington’s disease and cystic fibrosis can provide accurate and informative results when delivered with appropriate context and counseling. Similarly, when properly interpreted in light of family history and other relevant information, the BRCA test that detects a mutation that increases risk for breast cancer can inform a woman whether she is at increased risk. In contrast, some tests offered for home use purport to inform consumers about their risk of developing complex diseases, such as diabetes and heart disease, in the absence of adequate validation. As we reported last year, a host of other factors affects whether a certain person will develop those diseases or cancer or whatever condition is being tested for, making it vital to work with a skilled genetic counselor trained to interpret what the results do and do not mean.
As for the do-it-yourself tests currently marketed to American consumers, some of them do not provide definitive information — they are selling probability calculations, and often there’s no way to know if the formulas on which they are based are reliable. For one thing, most diseases have multi-factorial and complex causes, with environment and lifestyle factors such as diet and exercise — as well as genetics — entering into the equation. As yet there’s no way to accurately predict the interplay of these to calculate a reliable probability. Another flaw: Genetic tests pinpoint an isolated gene or part of the genome that has been identified as contributing to an illness, such as a particular kind of cancer, when in fact many genes are actually involved, some as yet undiscovered.
Clearly, further investigation and regulation is required. In the meantime, the American College of Medical Genetics (www.acmg.net) has issued five minimum requirements that you should look for before agreeing to take any genetic test…
There are a wide range of tests marketed DTC — some are diagnostic, others are predictive, and the amount of evidence for both is highly variable. Therefore it is not possible to draw conclusions that most are or are not valuable and useful. “In my perspective, the key issue is that because of a lack of oversight, it is not possible for consumers to tell the difference between valid and not valid,” says Javitt, noting that the only way to separate the wheat from the chaff is by close evaluation of the scientific literature on each test, something consumers may lack the knowledge of how to do. In our opinion, that’s what experts are for.
