Genetic testing from home, no more a science-fiction

Genetic testing may sound like a bit of science-fiction, but go online and you'll find at-home kits for everything from diabetes to Alzheimer's. Now, the market is expanding to include tests for psychiatric conditions like bipolar disorder that critics say may be more fiction than science. "I won't go so far as to say it's meaningless; it's just that we don't know what the meaning is," said Dr. Michael C. Miller, editor-in-chief of the Harvard Mental Health Letter. There are about 1,500 genetic tests available, both through medical professionals and directly to consumers, but the data on the validity and usefulness of those tests is incomplete. The associations being found between genes and specific ailments are modest at best, said Dr. Muin Khoury, director of the National Office of Public Health Genomics at the Centres for Disease Control and Prevention (CDC). "We can't just go from a discovered gene to having tools on the market applied willy-nilly without validation," Khoury said. "It's not only that they're not doing any good to people, but they may do some harm right now. We don't know the extent to which people will react to this kind of incomplete information."

One of the first commercially available psychiatric tests, made by Psynomics, is intended to reveal an increased risk of developing bipolar disorder by testing for a gene variation that has been associated with the mental illness in studies. "The tests are designed to provide objective data for use by doctors in combination with their other evaluations to arrive at a more timely and accurate diagnosis of a patient's condition and the right therapy," the company said in a press release announcing the availability of the tests. The $399 kit uses a saliva sample to test for one of the likely dozens of genes associated with bipolar disorder, GRK3; the results and a report are mailed to your physician. The company's website states that if you have the gene, you are two to three times more likely to have the disorder, depending on the particular gene variation found. Psynomics also tests for genes that may influence how you respond to serotonin-based drugs often prescribed for depression and bipolar disorder in order to recommend treatments that may help.

But the test cannot give a definitive diagnosis or predict future risk of developing the disorder, and a negative test does not rule out bipolar disorder. As well, the test results are only valid for Caucasians with Northern European ancestry who have at least one relative with bipolar disorder, and who are exhibiting symptoms of the disease themselves. Other companies are working on tests aimed at psychiatric disorders, including depression and schizophrenia. Several studies have associated various genes with bipolar disorder and schizophrenia, but results associating a gene with a disorder are often difficult to replicate. A gene may show a connection to a disorder in one study but not in a follow-up evaluation, Miller said.

"We're at the stage where we know that there are certain areas of the genome that are implicated or associated with one disorder or another," he said. "But until we actually know what that gene does, it's going to be hard for us to figure out where it fits in." The genetic components behind psychiatric disorders are unclear because the illnesses are the result of the interplay between many genes, as well as environmental factors. With more knowledge about what those genes are, what they do in the body and how they interact with each other, genetic testing for them may become valuable in the future, Miller said, but the science isn't yet clinically useful.

"All we have are bits of information," he said. "They haven't really strung yet into a full sentence, a full paragraph, a chapter that we can make sense of in a meaningful way in the clinic." What it boils down to is that the information provided by the existing tests don't add or subtract anything of value, Miller said. They just provide a result that may confuse more than it clarifies. "Sometimes a little knowledge is a bad thing," he said, "especially if you don't know how to interpret it." There is also the issue of privacy. On Thursday, Congress passed a bill that protects individuals against discrimination based on genetics. But putting your genes -- especially as related to psychiatric health -- on record, could still come back to haunt you later, warned Miller, adding that mental health is still poorly understood, which allows a person's psychiatric history to be manipulated.

The American Psychiatric Association doesn't yet have an official policy on genetic testing, and the Food and Drug Administration does not examine the available tests to confirm accuracy. But the FDA is working on standards for the genetic testing industry, and the Federal Trade Commission released a fact sheet advising consumers to be wary of claims made by companies. "Currently the status of oversight is very relaxed and lenient and confusing at best," CDC's Khoury said. They are not involved in oversight, but the CDC is studying genetic tests and their applications, and Khoury said the government agency is advocating for more aggressive translation research, a new area in genomics. via Reuters.

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