Subscribe to one of our feeds
Print
“People are getting these tests because they believe the science is all-powerful. They do not understand the nascent state of genetics.”
Empowerment through genetics is now at everyone’s fingertips—or so we’re told. A quick trip online will direct you to tests that claim to identify your genetic propensity for diabetes, breast cancer, cystic fibrosis, or iron overload disease. You can secretly check your baby’s paternity and learn its gender in as few as six weeks from conception. You can go to Target.com and buy a genetic home collection kit for the whole family, with results that tell you how your DNA makes you unique. Two new companies, Navigenics and 23andme, even go beyond individual tests and promise to bring whole-genome scanning home to everyone.
“Your genes offer a road map to optimal health,” Navigenics asserts in its marketing blurb. When consumers get their hands on information about their own genomes, according to this Silicon Valley startup, they’ll be able to find out what conditions they’re likely to get later in life and start preventing them now.
But what kind of a road map do our genes really offer?
Despite the glamour and the hype, many geneticists are turning away from DNA as the definitive answer to health and longevity. Understanding disease, they have come to believe, will require more than pinpointing the responsible polymorphisms, or genetic variations. High-throughput sequencing tools have dramatically boosted reports of gene-disease associations. Yet there are, warns Muin Khoury, director of the National Office of Public Health Genomics, in a letter with four colleagues to PloS Medicine, troubling inconsistencies in the underlying studies as well as the systematic reviews that cite them. In many cases environmental contributors to disease, like smoking in lung cancer, far outweigh variation in genetic susceptibility.
The original funders of the Human Genome Project—the National Institutes of Health and the Department of Energy—increasingly describe human health as a complex equation built from many factors that interact with an individual’s DNA. Chemicals in the environment can control gene expression. Behavior and diet can alter the chromosomes without any change in the nucleotide sequence itself—yet shift gene activity for generations. Biological networks outside the cell can influence its internal operations. No one is throwing away the genome—geneticists are leading this science, after all—but the latest research is making it clear that our DNA is neither a book of truth nor a magic guide to treatment decisions.
Even so, the message of increasing complexity hasn’t yet filtered out of the lab and into the consumer marketplace. “The only support for this kind of testing right now is genetic determinism,” says Edward R.B. McCabe, who heads UCLA’s pediatrics department and is also physician-in-chief of Mattel Children’s Hospital. The whole-genome screens may be worst of all, according to McCabe, potentially sending people off on an anxious, endless search for answers to unexplainable single-nucleotide variations. “People are getting these tests because they believe the science is all-powerful. They do not understand the nascent state of genetics.”
Why would they? The rapid-fire announcements that tie disease susceptibility to specific gene variations haven’t slowed. Science-savvy consumers want to know how the findings relate to their own lives. They may not get answers from their doctors, who often have a thin knowledge of and lack of comfort with genetics. People also may be skeptical about the ability of the healthcare system to apply new genetics tools when time is short and costs high.
Consumers have become more comfortable taking a stronger hand in their own healthcare decisions, spurred by trends such as direct-to-consumer pharmaceutical ads and pre-tax health savings accounts. Home tests for pregnancy, hepatitis C, prostate-specific antigen, and lipid levels can easily be found at the drugstore or on the Web. Even HIV screening, once thought only appropriate to deliver in a health care setting, now can be handled through a mail-in kit and follow-up call to learn the results. Going online to seek and to share health information is common, with four of five Internet users having used the Web for this purpose. Sites that sell at-home genetic tests highlight these trends and inform consumers that they can now get cutting-edge personalized medicine in the privacy and comfort of their own homes.
The flood of news and marketing and the lure of the genome have generated a sort of Wild West of online genetic testing. Demand does seem strong, but the U.S. Food and Drug Administration (FDA) has taken little responsibility for quality control. Genetic science is exploding, but the significance and usefulness of these tests remain to be seen. In some cases, it’s even questionable whether any DNA is being analyzed. The very proliferation of testing options and claims has created an opportunity for startups such as Redwood Shores, California-based Navigenics, which promises to cut through the confusion and deliver consumer-directed genetic screening services tied directly to clinical medicine. In a similar vein, 23andme in nearby Mountain View offers to help “make sense of your own genetic blueprint.”
