We previously reported that direct-to-consumer genetic tests can spur positive lifestyle changes, but we're back to warn you that a recent study done at Emory University in Atlanta has shown that the results of the at-home kits can vary widely. Not only that, but a Google search here at ThirdAge.com revealed that two of the companies in the study, deCODEme, and Navigenics, are no longer selling their products. However, customers who had already used the kits can still get their results, which is reason enough to pay attention to divergent findings of the Emory team! The link to deCODEme leads to a page that says: "Sales of Genetic Scans direct to consumer through deCODEme have been discontinued!" The link to Navigenics takes us to a page that says: "We are no longer accepting orders or samples for the Navigenics Health Compass service." The third company, 23andMe, is still in business.
A release from Emory quotes lead researcher Cecile Janssens as confirming the demise of deCODEme and Navigencis "Although two of the companies that we studied are no longer operating, genotyping and sequencing is becoming less expensive and testing such as this is increasingly popular," she said. "The methods used for predicting these types of results are of important concern."
Janssens and colleagues published their findings online in the journal Genetics in Medicine. Test results provided by the three companies at the time of the study indicated an individual's risks for a large number of diseases. The study was conducted by creating DNA datafor a hypothetical population of 100,000 individuals, which is "a less expensive and equally valid method for demonstrating the variations in predicted risk among the companies," according to the release. Predicted risks, which were calculated using the methods of the three companies detailed on their websites, were assessed and compared for six diseases:type 2 diabetes, prostate cancer, celiac disease, Crohn disease, age-related vision loss, and abnormal heart rhythm. The variations in predicted risks were explained by three factors: *The companies considered a different number of genetic variants in the risk calculations.Generally a larger difference in the number of variants implied more variation in predicted risks. *All three companies used an estimate for the average population disease risk as a starting point for their predictions. Differences in average risks affect predicted risks of all consumers to the same extent.For example, when the average odds is two times higher, all predicted odds are also two times higher.
*The companies applied different mathematical formulas. The formulas of two companies led to an overestimation of risks when predicted risks were higher and even predicted risks that were higher than 100 percent. "Our study provides insight into the methodology and performance of risk estimation for personal genome tests," Janssens explains. "Future efforts to design predictive models will benefit from understanding the strengths and limitations of these current models and formulas."
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Genetic Test Kit Results Vary