For $1,000 and up, several new companies will scan an individual’s entire genome for clues about ancestry, potential health limitations and the inheritance of traits such as lactose intolerance. Clients can compare their DNA with a celebrity’s or invite friends and family members to share genetic profiles. Despite the comprehensive reports and background data these Web-based services deliver, some observers believe the information is more recreational than relevant.
Direct-to-consumer genetic tests have existed for at least a decade, and in recent years the number of choices has exploded. Whereas most of these offerings probe for only a small number of gene variants, advances in genome chips now allow a quick, inexpensive search for a wide range of targets all at once. Navigenics in Redwood Shores, Calif., 23andMe in Mountain View, Calif., and deCODE Genetics in Reykjavik, Iceland, recently began scanning for markers associated with as many as two dozen conditions and traits. And for upward of $350,000, Knome in Cambridge, Mass., enables customers to join J. Craig Venter and James D. Watson in the elite cadre of humans who have had their entire genome sequenced, analyzed and interpreted.
With new tools, reference sequences and big study populations in hand, geneticists have found increasingly robust associations between DNA variations and disease susceptibility. But the data are still incomplete and sometimes conflicting, cautions Muin Khoury, director of the Centers for Disease Control and Prevention’s public health genomics office. For now, he says, sequencing one’s genome or scanning for susceptibility markers offers “no useful information.”
Except in the case of rare disorders caused by a single gene variant, having a genetic susceptibility is far from a guarantee of falling ill. Multiple genes interact within a complex biological system that includes many other important players, among them RNA and chemicals in the environment. Complex conditions such as diabetes or heart disease have myriad behavioral and environmental components working in concert with an unknown number of genes.
With so much still to learn, it is too early to use results from gene association studies for health-planning purposes, according to Khoury. Besides, he points out, it is unclear in the medical literature whether news about genetic susceptibility to particular conditions has any power to change people’s habits. Moreover, physicians are unsure how to apply the drug metabolism information from pharmacogenomics tests in their prescribing decisions. And in some cases, the tests offered online seem altogether disconnected from genetic medicine. A July 2006 U.S. Government Accountability Office study of services provided by nutrigenetics companies questioned whether, in some cases, any DNA was analyzed at all. The agency concluded that the firms “mislead consumers by making predictions that are medically unproven.”
The new genotyping companies claim to cut through the confusion by delivering high-quality, responsible science. They stop short of offering medical services and instead promote their scans as an innovative means to provide health information and empower consumers to act on it. While genetics research moves forward, the companies say, people can start working now with their doctors or take steps to change their diet or other behaviors. “It’s better to start than to wait an indefinite period of time until the science is perfect,” insists Mari Baker, chief executive of Navigenics. Not all of the 1.8 million points her company scans on the genome are informative today, she says, but customers will be able to access ongoing findings as they come in. Eventually Navigenics plans to incorporate other health data, such as family history and medication use.
Some experts worry that the rollout strategy could backfire. Because the relevance of whole-genome scans is so limited, warns Sharon Terry, president and chief executive of the advocacy group Genetic Alliance, “the average person may lose interest before there is enough information to have utility.” Along with creating tools such as an online guide to family health history and a WikiGenetics Web site, Genetic Alliance is pressing for regulations that would protect against discrimination, safeguard privacy, and require quality and validity testing. So far efforts to extend laws into these areas have failed.
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4 Comments
Add CommentDo not waste you hard-earned money on gene testing. I just finished reading J. Craig Venter's "A Life Decoded". Buy the book, read it, and save $975.00.
Reply | Report Abuse | Link to thisYes. It appears as though there are too many genetic and environmental variables to predict, with reasonable medical certainty, whether information one recieves from personal genome scans can be helpful. My cousin had her breasts preemptively removed due to the fear instilled by knowledge of genetic markers and family history, however, she had no cancer cells at the time of her decision to go forward with the radical procedure.
Reply | Report Abuse | Link to thisHow tragic! My wife's aunt had a tonsillectomy in the 1930s, (when that was the thing to do then), and subsequently died from improperly administered anesthesia. She was in her early twenties. Sometimes elective surgery can be a bad thing.
Reply | Report Abuse | Link to thisConsidering that a harmful mutation of BRAC1 or BRAC2 is 60% likely to cause breast or ovarian cancer in a woman, and that such cancers do not have a good early detection or survival rate; preemptive surgery may present a lower risk to the woman. Family history, personal history, and physical examination must accompany the genetic testing in determining that risk.
Reply | Report Abuse | Link to thisIn medicine, there is never such a thing as a sure thing; except that we will all eventually die.
Tom Mitchell's cousin may have doubled her life expectancy by having the mastectomy. If she HAD had cancer cells present, then it wouldn't have been preemptive surgery.
Hugh Jones' wife's aunt's death during a tonsillectomy in the 1930s isn't surprising or unusual. Most anesthesiologists didn't have much of an idea of what they were doing back then, being barely better than stone knives and bearskins as Doctor McCoy was fond of saying. Today's anesthesiologists are several orders of magnitude more knowledgeable than they were in the '30s; and 5 to 10 times safer than they were even as little as 10 years ago.