April 3 (Bloomberg) -- Genetic testing to determine how a person responds to medications may create more confusion than clarity about health risks, according to an article in the journal Science.

The tests may one day pave the way for personalized medicine, when a survey of each individual's genes can be used to tailor their care, according to the article. So far, few studies have identified genes that alter how someone responds to drug therapy and even fewer have shown that care based on genetics improves results.

Sara Katsanis, Gail Javitt and Kathy Hudson, researchers from Johns Hopkins University's genetics and public policy center in Washington, D.C., said the government needs to better regulate the genetic test industry. They proposed creating a mandatory, public registry to include information supporting the intended use of the tests, along with more federal oversight.

``Today there is no mechanism to ensure that genetic tests are supported by adequate evidence before they are marketed or that marketing claims for such tests are truthful,'' they wrote. ``Misleading claims about tests may lead health-care providers and patients to make inappropriate decisions about whether to test or how to interpret the results.''

The article discusses as an example tests for variants in the CYP450 genes, which can determine how quickly a person's body processes popular anti-depressants including Wyeth's Effexor, GlaxoSmithKline Plc's Paxil and Forest Laboratories Inc.'s Lexapro. A test of the two genes was approved by the U.S. Food and Drug Administration and later discouraged the U.S. Centers for Disease Control and Prevention in 2004, the researchers said.

Direct Sellers

More than dozen companies sell genetic tests, including Servx, DNA Direct, LabCorp, Roche Holding AG, Genelex and Laboratory Corporation of America Holdings. DNA Direct and Genelex market the tests directly to the public, bypassing doctors, who could help consumers interpret and use the findings, according to the article.

Someone who learns their CYP450 gene profile might take less or more medicine ``with adverse health outcomes,'' Katsanis, Javitt and Hudson wrote. ``The current situation also could lead both providers and patients to lose trust in the value of genetic testing to improve drug-prescribing decisions.''

Greater regulation proposed by in the article would slow the use of DNA testing to manage drug use, said Kristine Ashcraft, director of operations at Genelex Corp. in Seattle. The company supports a consumer guide to help people determine if they need gene tests, she said.

Genotype Rights

``Individuals have a right to learn their genotype and control that information,'' Ashcraft said. ``If patients are denied direct access to this testing, they may be reluctant to be tested because they are not confident that the confidentiality of the test results will be adequately protected.''

Several other companies, including 23andme Inc. and DeCode Genetics Inc., also market tests for genetic variants to help consumers understand their personal health risks.

The FDA should ensure that all the tests accurately detect key genetic variations and the Federal Trade Commission should enforce rules about misleading advertising claims for the tests, they wrote.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

Last Updated: April 3, 2008 17:26 EDT