Several geneticists, including Craig Venter, have authored a commentary in Nature on direct-to-consumer genetic testing. (Nature Article) They looked at tests from two popular DTC companies and found that there were frequent divergences in the risk of disease reported on the same individuals. They analyze possible explanations for this divergence and suggest steps to improve the utility and trustworthiness of the results of genetic tests.
Among the suggestions: report how much of overall risk for a disease is accounted for by the markers tested; focus on high-risk predictions; directly genotype the risk marker, not a surrogate marker in linkage disequilibrium; always report on pharmacogenomic markers, which have important usefulness in avoiding adverse drug reactions; monitor the behavior of consumers receiving the test results; carry out prospective studies to strengthen the prediction power of markers and eventually move to full sequencing, not genotyping.
This commentary highlights the need for genetic testing to be as certain and as well-explained to consumers as possible if it is to continue to move into the mainstream of medical care. Any issues or problems heighten the likelihood of enhanced government regulation, which unfortunately often does as much harm as good. This aspect of personalized medicine has great potential value, not the least of which is aiding in patient involvement and engagement, but it needs to be very trustworthy.