Tuesday, July 15, 2008
As genetic testing becomes more widely understood and administered, Karen Ravn for the Los Angeles Times questions whether the costs (and hidden costs) of genetic testing are actually worth it. Ravn writes,
Everyone agrees that the science of gene testing is imperfect, but the companies offering tests directly to consumers, along with their supporters, say the information they give is valid and valuable, noting that clients can get updates as more is learned.
Critics aren't so sure that the people being tested always get their money's worth. And many believe that even when gene tests and claims about links to diseases are accurate, they may be confusing. "This kind of testing, this kind of knowledge about ourselves, is so new," says Dr. Edward McCabe, co-director of the UCLA Center for Society and Genetics. "We can get a whole lot of information, and we're not going to know what a lot of it means."
Some testing companies work hard to solve this problem. For example, Navigenics of Redwood Shores employs three highly trained full-time genetic counselors, one of whom is assigned to each client.
Still, says Dr. Robert Nussbaum, chief of the Division of Medical Genetics at UC San Francisco, no matter how well it's explained, some of the information people get simply doesn't mean much. Some DNA tests are highly predictive of disease -- for example, tests for mutations in the cystic fibrosis gene -- but others are based on flawed data or so weakly predictive that many who test negative will end up getting the disease, while many who test positive will not (an example would be tests for risk of Type 2 diabetes).
In such cases, Nussbaum says, "the information is basically useless." It might even be counterproductive, he adds, if someone who tests negative -- for, say, diabetes risk -- then has less incentive to adopt healthful life habits.
Even highly predictive tests can be unhelpful if they predict conditions that can't be treated or prevented, such as Huntington's disease, Nussbaum adds. They can simply make a client worried or scared.
In all, says Hank Greely, director of the Center for Law and the Biosciences at Stanford University, while some companies clearly provide useful information to their clients, "some companies provide nothing beyond a new way of wasting money."