Whole-Genome Scans Not Ready for Widespread Use?
Tests are promising but not yet reliable enough, experts say
By Amy Norton
TUESDAY, March 11, 2014 (HealthDay News) -- Commercially available tests can analyze your genetic profile and try to predict your risk of a host of diseases. But a new study suggests they aren't ready for prime time.
The technology, known as whole-genome sequencing, allows scientists to "map" the information encoded in most of the billions of building blocks that make up a person's DNA.
So far, whole-genome sequencing has been used mainly in research. But the hope is that the technology will help fuel a new era of "personalized medicine" -- where doctors will be able to identify patients with gene variants that raise their risk of certain diseases.
In the past few years, the cost of whole-genome sequencing has fallen to the point where it could soon be feasible to use it in everyday health care, said Dr. Frederick Dewey, of Stanford University, the lead researcher on the new study.
But based on his team's findings, Dewey said, a lot more work is needed before that idea becomes reality.
The study, reported in the March 12 issue of the Journal of the American Medical Association, found that sequencing a whole genome remains a fairly daunting task.
And although the commercially available tests are good, they aren't yet reliable enough for routine patient care, Dewey said.
For the study, Dewey's team recruited 12 healthy adults who volunteered a blood sample for whole-genome sequencing.
Overall, testing showed that each patient had between 2 million and 3 million unique variations in their DNA. The researchers then used a software program they had developed to whittle down that sea of information to around 100 genetic variations per person that were deemed worthy of more investigation.
Next, they analyzed those variations in an old-fashioned way -- by "actually sitting down," Dewey said, and sifting through the medical literature and available genetic databases to see which gene variants might be relevant to people's health.
That process took about an hour per variant, at an estimated cost of $17,000 per patient when all was said and done.
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.