October 7, 2009 / 11:14 PM / 10 years ago

Two consumer gene tests give conflicting results

* Genome scientist Venter tests two products

* Consumers should be clear about tests’ shortcomings

By Julie Steenhuysen

CHICAGO, Oct 7 (Reuters) - People who send their DNA away to gene testing companies hoping for an accurate picture of their future risks for inherited diseases should beware. The results are not ready for prime time, says genome pioneer Craig Venter.

“At this stage, they should mostly be taken with a grain of salt,” said Venter, who was awarded the National Medal of Science on Wednesday by President Barack Obama for his work to advance the science of genomics.

Scientists have identified more than 1,000 variations of genes linked to different diseases, and companies are using that information to develop tests sold directly to consumers that handicap their risk for developing various diseases.

Venter and colleagues Pauline Ng of the J. Craig Venter Institute in San Diego and Sarah Murray of Scripps Translational Science Institute in La Jolla , California, put two of these products to the test.

Using test kits provided by California-based firms Navigenics Inc, a private company, and 23andMe, backed by Google Inc, they analyzed results from five people who took both.

“We just compared the results,” Venter said in a telephone interview.

What they found is that while the tests are highly accurate at generating raw genetic information, they often disagree over what the tests mean about a person’s disease risk.

For four diseases, the predictions between the two companies completely agree for all individuals, but for the most part, the tests offered conflicting results.

“For seven diseases, 50 percent or less of the predictions of two companies agreed across five individuals,” Venter and colleagues wrote.

Celiac disease, a nutritional disorder, is one condition for which predictions agreed between the two companies among all five people in the study.

That was because both companies used one genetic marker that plays a big role in a person’s risk of developing Celiac disease. For other diseases, the companies used different genetic markers to determine a person’s risk profile.

Venter said the tests typically are just looking for common changes in the genetic code. “A lot of those common changes aren’t that accurate at assessing the risk for real disease,” he said.

They also do not account for the positive traits a person may have inherited that protect against disease. And gene tests cannot account for healthy or unhealthy lifestyles.

“All genetics will give us at the best will be statistical probabilities. Even so, we want those to be accurate and meaningful,” Venter said.

He said that will take large, long-term studies.

Venter said while the tests do provide useful information that can help people modify their behavior, people should be aware that the science is very young.

“Even this little study shows how early and primitive we are in our understanding of the human genome,” he said.

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