Navigenics and 23andMe issued an open, joint letter to Nature yesterday in response to an opinion article on direct-to-consumer genetic testing that appeared in the journal last month.
In that paper, senior author Craig Venter and his colleagues reported that they had found disparities in the risks reported for seven diseases when they compared Navigenics and 23andMe test results. The authors also offered a set of recommendations to improve such testing.
"Our companies agree with most of the recommendations," Navigenics and 23andMe wrote. "More work must be done to standardize markers used; to better explain the contribution of genetics to common, complex diseases; and to incorporate common genetic variants into clinical practice."
But while both companies supported many of the paper's recommendations, each felt the DTC test results and/or recommendations described in the article required clarification.
For instance, Navigenics noted that there are many ways to report genetic test results, making it difficult to precisely report the genetic contribution behind some disease markers. "[T]he call for such information must be put in context with currently implemented non-genetic risk communication," the authors wrote. "Clearly, risk communication has, and will continue to be, an important area of research for the community."
The company also pointed out that it is already incorporating some of the paper's recommendations into its service, including the notion that companies should not focus on results related to "less than average risk." Navigenics also highlighted its participation in studies aimed at understand the long-term behavioral consequences of learning genetic risk information.
Meanwhile, 23andMe argued that the authors of the opinion paper used a "somewhat restrictive" definition of average risk in their analysis, looking at risk increases or decreases of five percent or more compared to relative risk.
"While there is no scientific consensus on what magnitude of risk equates with 'meaningful' increased risk, one typically does not find relative risks less than 1.5 used today in clinical practice," 23andMe wrote. "Thus, it would have been more appropriate to perform the consistency comparison using a wider window for 'average risk.'"
23andMe also took exception to the way the researchers quantified the genetic contribution to disease, suggesting the methods used were more appropriate for population analyses than studies of individuals.
"[B]oth our companies thank [the authors] for their serious consideration of genomics and personalized medicine," the authors concluded. "We welcome further dialogue on how best to improve our offerings to the public."
Although the letter was intended for Nature's editor, both Navigenics and 23andMe noted that the journal did not publish the article "because of space restrictions." Consequently, the companies decided to post the letter on their web sites.