Putting DNA to the test

The availability of affordable, direct-to-consumer genetic tests has grown rapidly, leaving regulation behind. Dozens of companies now offer inexpensive at-home kits that allow people to spit into tubes, send samples for DNA analysis, and receive a report that purportedly linked their ancestry or their potential susceptibility to a long list of disorders. have – often weakly – specific genes to do.

But the value of these tests remains a matter of debate, which is why the industry needs a strong set of quality standards and codes of conduct to protect both its consumers and its credibility.

The UK Human Genetics Commission (HGC) took a welcome step in that direction last month when it released a set of principles to guide consumers and promote higher standards and consistency among personal-genomics providers.

But HGC’s guiding principles — which are subject to public review as of early December — focus largely on companies’ promotional messages to reflect the limited usefulness of genetic testing, and to make customers more aware of it. for what they can realistically expect to learn from the tests. Most DNA testing companies say they are already doing the same, emphasizing that what they provide is information, not a medical diagnosis.

The question is what happens when prices drop further and tests become more popular. They’re already being marketed on the Internet with little oversight, and it seems that an increasing number of people will be turning to personal-genomics companies in search of definitive answers on how to improve or protect their health.

But the available answers are becoming increasingly less certain: an increasing number of genome-wide association studies, which provide a plethora of genetic markers for disease risks, provide results that may be difficult for even researchers to interpret. and often flag markers that are not the most useful predictors of complex traits (see page 712).

This means that clients will often receive results stating that they face the vague possibility of a somewhat increased risk of a little-understood disorder. Presumably, in that case most customers would be more cautious about disease screening. But if the vague, slightly elevated risk is related to a frightening condition like breast cancer, some individuals may feel compelled to take drastic and perhaps unnecessary measures, such as a prophylactic mastectomy.

The principles of HGC, if adopted, should help reduce such panic reactions. For example, the HGC advocates that genetic counseling be provided before and after testing for serious hereditary diseases. But there is room to go further and, on page 724, Craig Venter and his colleagues give nine recommendations for doing so.

For example, Venter’s team urges companies to agree on a basic set of non-ambiguous genetic markers — those that put a carrier at higher risk of developing a specific condition. Companies would be advised to adhere to this recommendation, as such an agreement would help avoid conflicting messages and inconsistent results across the industry.

Ultimately, however, government regulators may be forced to act on the grounds that industry self-policing no longer provides adequate protection to consumers. The US Food and Drug Administration has already recruited bioethicist Alta Charo to advise Commissioner Peggy Hamburg on a comprehensive approach to regulating these tests.

Given the rapid pace at which the science of personal genomics is advancing, government regulators should proceed with caution. But in the interim, DNA-testing providers should do so by simply providing clinically useful information and explaining how much of the biology is unknown.

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