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Whole-Genome Scans Not Ready for Widespread Use?

Tests are promising but not yet reliable enough, experts say
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And what came from the effort? The researchers ended up with about two to six DNA variations for each person that they considered potentially important.

In the end, only one study participant had a test result that needed clear action -- but it was a big discovery. The woman carried a mutation in the BRCA1 gene, which carries a high risk of breast and ovarian cancers. She ultimately chose to have her ovaries removed and start more intensive breast cancer screening.

"The promise of this [technology] is great, and our study highlights some of the opportunities," Dewey said. "You can identify clinically meaningful disease risks."

But, he added, the study also pinpoints the limitations and challenges of whole-genome sequencing as it stands now.

"We have to be honest about what we can reasonably expect this technology to do," Dewey said.

In particular, his team found that two commercially available whole-genome tests are not yet accurate enough to rely on for routine use. The tests were not able to reliably detect all variations in 7 percent to 16 percent of 56 genes that are known to be associated with disease risks.

"There's still a gap between where we are and what would be clinically acceptable," Dewey said.

Even if the sequencing technology were perfect, that would still leave the question of what to do with all the genetic information, said Dr. William Feero, of Maine Dartmouth Family Medicine Residency, in Augusta.

"Trying to determine what's meaningful is quite challenging," said Feero, who wrote an editorial published with the study.

Much of what's known about the genetic underpinnings of disease is confined to what's called the "exome" -- the genes that make the proteins that run your body. But the exome accounts for only about 1 percent of the entire genome. The vast sea of genetic material beyond that was once thought of as "junk DNA," Feero said.

Scientists have known for a while that's not true -- that DNA has a number of important jobs, including regulating the protein-making genes of the exome. But Feero and Dewey both said much more remains to be learned about DNA variations and disease risk.

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