Direct-to-Consumer Genetic Testing: Reliable or Risky?

In recent years there has been a dramatic increase in the discovery of information related to the genetic risk of disease, as well as in the technical ability to accurately measure an individual's genotype. These advances underlie the promise of personalized medicine, in which a patient's genotype informs the medical care they receive. Private companies are attempting to capitalize on these advances by providing direct-to-consumer (DTC)6 genetic testing that estimates the risk of disease for a customer, given their genotype. Because these tests make claims about medical conditions, they have come under scrutiny by regulatory agencies. We ask experts in the field to comment on several issues relevant to DTC genetic testing.DTC genetic testing is based primarily on associations between common genetic variants and disease. Do we have enough evidence about these associations to use them as genetic tests? Eric Topol: Yes, without question, in select circumstances. For several pharmacogenomic interactions, the information can be especially valuable for an individual to avoid a major adverse side effect (as with carbamazepine) or to ensure efficacy (clopidogrel). Also, when there is clear evidence of heightened risk (e.g., 2-fold or greater) for a common disease, such as diabetes, heart attack, colon, melanoma, or other cancers, there can be actionable information to get appropriate screening (e.g., colonoscopy) or potential preventive steps (e.g., protection from the sun). As we move toward sequencing and identification of rare or low-frequency variants that have high penetrance, it is unlikely that the heightened risk from the previously identified common variants will go away.James Evans: We clearly do not. This is best demonstrated by several straightforward studies in which the same sample was sent to leading DTC companies for analysis. The results included wildly divergent risk estimates, with companies reporting “above average,” “below average,” and “average” risks …