One woman panicked when the genetic test she ordered over the Internet concluded that her son was carrying a life-threatening disorder and, even more disturbingly, that he was not — genetically — her son. Another, who always thought she was white, was flabbergasted to find her genes were mostly of African origin. A third woman’s result was still more stunning: She was a man, it said.

“I thought, ‘Oh my god. Am I really a man?’” said Denise Weinrich, 48, of St. Peters, Mo. “I thought: ‘What’s the matter with me? … How am I going to tell my children?’ DNA doesn’t lie.”

DNA does not lie, but its truth is often elusive.

Weinrich was one of 87 people who received incorrect results last month because of a laboratory mix-up involving customers of 23andMe, a testing company backed in part by Google. The Mountain View, Calif., testing company says it regrets the incident and noted that it spotted the mistakes quickly, notified the clients and has taken steps to prevent future errors.

But the blunder has fueled a debate over whether the government should more aggressively police the proliferating tests. Critics say too many make claims that go far beyond the science, yield results too complicated for people to interpret on their own or are just plain wrong. Others, however, fear more federal oversight will make the tests too expensive and hard to get.

“If you have things completely unregulated, then you have a Wild West of commercial interests around medical information,” said Robert Green, director of Boston University’s Center for Translational Genomics and Health Outcomes. “If you overregulate, you run the risk of stifling innovation in a very dynamic industry.”

New frontiers

Genetic testing has become one of the flash points in the larger question raised by new technologies that are fueling a movement toward more unfettered access to information: When does government intervention cross from prudent and necessary to intrusive and paternalistic?

Dozens of companies offer tests that claim to tell people everything from what foods they should eat to live longer and what cosmetics they should use to whether they are at risk for cancer, Alzheimer’s and other ailments, and how some prescription medications will affect them. Many think that genetic testing is key for the future of “personalized medicine,” which tailors cures to people’s genes. But few tests have undergone stringent scientific validation.

Mounting concerns have prompted the Food and Drug Administration, which has long resisted calls to regulate the field, to begin stepping in. In May, the agency scuttled plans by Pathway Genomics of San Diego to sell genetic tests in Walgreens stores. Several weeks later, the FDA sent letters to five companies that were selling tests over the Internet, declaring that their kits are medical devices and must undergo federal scrutiny. This week, the agency is convening a public hearing to debate what regulatory role it should play.

“It’s come to the point where really there’s a need for some oversight,” said Alberto Gutierrez, who heads the FDA’s Office of In Vitro Diagnostics. Results from questionable tests can be unnecessarily alarming, Gutierrez said, adding that some women have undergone surgery, for example, based on tests that purport to gauge the risk for ovarian cancer.

“We know of reports of people who have found a test, found a doctor that is willing to order the test since they are so afraid of the disease and even removed ovaries based on questionable results,” Gutierrez said. What’s more, without a genetic expert to interpret the often-nuanced results of valid tests, patients who test negative might be falsely reassured, critics argue. Women might think they are safe from breast cancer, for example, and stop getting mammograms without realizing that they might still be in danger because of genes not included in the test or other factors.

“That’s my nightmare scenario,” said Hank Greely, director of Stanford University’s Center for Law and the Biosciences. Even when the results are accurate, public perceptions often exaggerate the current power of genetic testing, many experts say.

“What one hears frequently is that simply knowledge of one’s various risks is a ‘road map to better health.’ That is profoundly inaccurate and premature,” said James Evans, a professor of genetics and medicine at the University of North Carolina in Chapel Hill. “We have little, if any, evidence that the provision of such information actually results in better health.”

The FDA did not want to specify what action the agency will consider at this week’s hearing.

Mandatory registry?

The National Institutes of Health is creating a registry to help consumers learn what genetic tests are available and evaluate their scientific validity. But signing up is voluntary for companies, and some experts argue that the first step should be to make the registry mandatory.

“What I think we need is greater transparency and information gathering about tests on the market, how that information is being reported to patients and how patients or doctors are using that information,” said Daniel Vorhaus, an attorney who edits of the Genomics Law Report, an online publication.

The tests provide people with information that motivates many to take steps to protect their health, others say, noting that laboratories are regulated through the federal Centers for Medicare and Medicaid to guarantee basic proficiency. The already-stretched FDA could become overwhelmed if it took on the task of going further and verifying the complex science underlying many of the tests’ claims, they argue.

“While regulations are sometimes necessary to protect consumers, people also need to remember that they come at a cost,” said Daniel MacArthur, who writes about genetic testing on his blog, Genetic Future.

Advocates for patients suffering from rare diseases are especially concerned companies will have little financial incentive to develop tests if increased regulation makes them too costly.

“The risk of losing these tests is significant,” said Michael Watson of the American College of Medical Genetics.

The prospect of greater FDA regulation is being met with mixed reaction by companies. Officials from several said they welcome reasonable new controls that might help eliminate less-scrupulous hawkers. Some also expressed concern about interference with the public’s access.

“If you look back a few decades, people were not told about their diagnosis of cancer, and it was thought we need to protect them from that information. Now that seems ridiculous,” said Joanna Mountain, senior director of research at 23andMe, which was co-founded by Anne Wojcicki, wife of Google’s Sergey Brin.

“The same thing goes for genetic information. We have many, many people who are very, very curious and want to know, and are capable of handling this information.”