FDA approves 23andMe’s at-home DNA test, but bathroom scale may work just as well for predicting health

One of the big stories last week was that 23andMe, a consumer genomics company, was the first company of its kind to receive FDA permission to provide information directly to consumers about their risk of developing diseases or conditions.

Although there are many companies offering at-home genetic testing–whereby a person sends in a saliva sample, along with between $100 to $2,000–the FDA’s blessing of 23andMe will give the company a leg-up in the competitive at-home genetic testing market.

Risky gene variants are not destiny

It’s important to know that simply having DNA variants associated with certain health conditions is no guarantee that a person will indeed develop these conditions. For example, people at increased genetic risk of cardiovascular disease are not at all destined to die from cardiovascular disease. Importantly, they also are at much lower risk if they follow a healthy lifestyle. This is potentially good news because it shows that for many conditions, risky gene variants are not destiny.

This nuance was something that the promoters of direct-to-consumer genetic testing spun to their advantage, arguing that if a person knows their genetic risk, they can make positive preemptive changes in their lifestyle.

Anne Wojcicki, the CEO of 23andMe, put it this way in an interview with the Wall Street Journal:

“Some people really want that information. They find it empowering. They may want to make diet and exercise changes, or retire earlier, or they may be able to detect symptoms earlier. And then the question is whether we can potentially intervene more effectively by learning the risk sooner.” She called the issue “really a question of personal choice.”

What the research says

However, as good as this sounds, just how responsive are people to information about genetic risk and lifestyle? So far, it doesn’t seem like it helps much. In a large analysis of all the studies done on this topic, scientists in the UK concluded:

“Expectations that communicating DNA based risk estimates changes behavior is not supported by existing evidence. These results do not support use of genetic testing or the search for risk-conferring gene variants for common complex diseases on the basis that they motivate risk-reducing behavior.”

Another important thing to remember is that for the vast majority of people, more exercise and healthier eating provides broad-based protection against numerous chronic conditions.

When I hear anecdotes about someone becoming more active and losing weight because they found out they are at mildly increased genetic risk for something like type 2 diabetes, it always makes me wonder why that motivated them more than all the important things we already know a healthy lifestyle can help with, such as preventing heart disease, cognitive decline, and cancer. If exercise and diet were drugs, they would be described as having a lot of positive “off-target” effects.

People respond differently to genetic test results, not always positively

There are a couple of other things to consider about direct-to-consumer genetic testing. First, some people who get a score back suggesting they are at increased risk might become fatalistic and figure there is nothing they can do. Or, some people who get a score back suggesting they are at decreased risk might become cavalier about their risk and assume they are protected no matter what they do.

There is also concern that people might become anxious if they find they are at increased risk, but so far that has not turned out to be a big issue. However, there is some evidence that direct-to-consumer genetic testing does increase physician utilization, perhaps for more testing and surveillance.

These possibilities of genetic testing are all in the early stages of investigation, and one thing is certain: In the next few years, we will learn more about how communicating genetic risks to generally healthy people affects how they feel about their health–and what they do about it.

The ‘bathroom scale’ risk assessment is free, easy and actionable

Finally, when the topic of gene scores comes up, I like to mention what I call the “bathroom scale score.” It turns out that for many common chronic diseases, body weight, BMI or waist circumference are more predictive of future risk than a gene score.

This information is free, easy to obtain and actionable. Unfortunately, it is also increasingly ignored. So my question to Ms. Wojcicki and the other enthusiasts: Do they really expect gene scores to succeed where bathroom scale scores have failed?

Michael Joyner is a medical researcher at the Mayo Clinic. These views are his own. He has done preclinical technical consulting for GSK, Amgen, Boston Scientific, Edwards, and Nonin on issues related to physiological monitoring, cardiovascular disease and diabetes. He is on the board of Xcede, a startup focused on tissue sealants. As a clinical anesthesiologist, he prescribes no drugs or products related to his consulting.