23andMe's genetic test on your drug reaction is ahead of its time

On Wednesday, the US Food and Drug Administration approved the first consumer DNA test that promises to tell buyers what drugs might best suit them based on their genetic profile. The manufacturer, 23andMe, has obtained FDA approval by paying close attention to what its test can do – so the approval underscores the limited usefulness of the test and everything we do not know yet about this area of medicine.

The test is linked to a drug segment called pharmacogenetics, which studies how genes influence our response to drugs. Variations in our genes can affect how quickly we break down a drug, how much we absorb, or how efficiently it gets to where it should be in the body.

The 23andMe test will tell consumers about 33 genetic variants associated with the effectiveness of common drugs – anticoagulants like Plavix and Coumadin – work, but it is explicit that consumers do not change their medications based on these results. The test is only supposed to provide potentially useful information that people can discuss with their doctor. To be approved, the company had to conduct a demographically representative study showing that 97% of users understood that the test was not a medical recommendation, says Kathy Hibbs, 23andMe's legal and regulatory manager. We do not know yet when the test will be available for purchase or how much it will cost.

Suppose you take the 23andMe test and report the results to your doctor. The doctor is still not supposed to suggest changing drugs before you get tested genetically again by an independent laboratory. "It seems to me that if a pharmacogenetic profile of a patient can affect drug-taking decisions, it's probably best to ask the doctor what tests can be done, because confirmatory tests are expected even if you have, "said Boadie Dunlop, a psychiatrist at Emory University, who is studying biomarkers to predict drug reactions. (Dunlop is also a consultant for the Assurex Health Personalized Medicine Society.)

For the moment, "there is very little evidence to support pharmacogenetic drug choice," adds Dunlop. He is also the author of an article that was published in Journal of Pharmacogenetics in May, this revealed that different pharmacogenetic tests can make different treatment recommendations.

The team analyzed four tests (CNSDose, Genecept, GeneSight and Neuropharmagen) and revealed that it could reliably detect if a person had a genetic variant, says Dunlop. But they do not necessarily test all the genes that might be important. The tests they studied also do not match the medical recommendations to make when they detect that a patient has a variant of the gene. "There are a lot of assumptions, and companies have their own proprietary algorithms, and that's where the recommendations vary the most," adds Dunlop. In fact, one day after 23andMe's approval, the FDA has warned against other tests not approved by the FDA that make such suggestions.

Even though 23andMe has gotten more FDA approval than other companies, that does not mean that its test is useful or necessary. Eric Topol, a geneticist from the Scripps Research Institute, points out that the analyzed genome variants are very limited. It's just too early. A magazine published by the American Psychiatric AssociationThe working group concluded that, although initial data on the genetic association and drugs were promising, there was insufficient evidence to justify the widespread use of pharmacogenetic testing. With respect to non-psychiatric medications like Plavix and Coumadin, various studies suggest that there is promising evidence of genetic-related treatment strategies, but also many unanswered questions.

In the end, we are all interested in making drugs more effective. But even if products promising a future full of personalized medicine are starting to appear in pharmacies, research still suggests that we are not yet at a stage where our genes can help us determine our dosages – for now.