Overrated “precision medicine” may just be serving vested interests, and consumer DNA testing can be useless—or even worse.
Today, you can get your DNA sequenced—the letters of your entire genetic code spelled out—for about a thousand dollars, a bargain compared to the $100 million or so it cost 20 years ago. And for around a hundred dollars, you can get partial DNA sequencing. Direct-to-consumer genetic testing is “only a click away,” like 23andMe, for “ancestry, health, love…and more.” Unfortunately, many tests that are available today haven’t been validated properly. And, as a result, the buyer may be buying something “that is ultimately useless.” Or, results may just be just flat-out wrong.
There is growing public demand for direct-to-consumer genetic tests, but when put to the test, researchers found an “alarmingly high false-positive rate.” Test results indicated that people carried a high-risk gene, but it simply wasn’t true. And this happened 40% of the time, especially with the BRCA breast cancer gene (the one Angelina Jolie publicly revealed she carries), which you can see below and at 1:08 in my video Should You Get Personalized Genetic Risk Testing?.
In addition to the 40% false-positive rate, some variants the tests did identify correctly were misclassified as being high risk when, in actuality, they weren’t high risk at all. You can see how it’s in these companies’ best interest to give scary outlier results, so customers will think the money spent was worth it and maybe even pay for additional testing. But false-positive results and variant misclassification can have serious consequences for a person, including unnecessary stress and even unnecessary medical procedures. What if you got a preventive double mastectomy because you falsely thought you were at high risk when you didn’t even have the BRCA mutation?
Yes, now, these genome-wide association studies have identified thousands of common genetic variants that affect the risk of complex diseases, as I talked about in my video on personalized nutrition. “Nevertheless, the discovered gene variants do not markedly expand our predictive ability compared with what can be achieved by using only information from long-known traditional risk factors.”
Take type 2 diabetes, for example. Researchers have identified about 50 genes that are linked to increased diabetes risk, but even when considered collectively, “obese persons with the lowest genetic risk for diabetes were nearly 5 times more likely to develop the disease than normal-weight persons with the highest genetic risk.” In other words, this would send out the wrong message to someone who is obese, giving them a false sense of security. Knowledge about type 2 diabetes genetic susceptibility based on what we know so far has “no implications for decisions about who should be targeted for intensive lifestyle interventions.” Everyone with excessive body fat, regardless of genetics, needs to slim down to reduce the risk of diabetes.
What about the famous study that purported to show that personally tailored dietary interventions could improve blood sugar responses, to the extent that some commentators said it raised questions about the usefulness of universal dietary recommendations? But if you actually read the study, the results do not show high interpersonal variation in relative blood sugar responses; do not show the model is superior to current methods of detecting high blood sugars; and do not show that personalized nutrition advice is better than standard dietary advice to manage high blood sugar responses after meals.
But what about personalized genetic risk counseling to at least motivate diabetes prevention? “In a somewhat forlorn bid to regain credibility, ‘knowledge’ of individual genetic risk profile has been touted as effective in motivating test-positive individuals to commit more strenuously to relevant disease prevention efforts….” However, again, available evidence doesn’t support that claim. And indeed, it did not seem to help those at risk for diabetes.
Researchers randomized people to get genetic tests worth hundreds or thousands of dollars to profile their subtle differences in risk for up to 40 different diseases. In this case, it was Navigenics that described its goal as empowering people with personal genetic insights to help motivate them to improve their health. Yet, it didn’t work. There were no measurable changes in diet or lifestyle, even in the short-term.
Randomizing people to personalized nutrition insights is like determining who might genetically benefit particularly well from eating more greens or eating to lower their cholesterol, yet when researchers put it to the test, there were no significant changes in diet at month six compared to those who didn’t get that personalized info, or even at month three. So, it’s no surprise there were no differences in weight, belly fat, cholesterol, or any of the other biomarkers.
Put all the studies together, and what do we find? There are no significant benefits to telling smokers who are at particular risk for lung cancer, or who need to eat especially healthy, or who should be more physically active. The bottom line: Expecting that being aware of DNA-based risk estimates will change behavior is not supported by existing evidence. However, that was the stated reason for the big presidential push for precision medicine in 2015: to empower individuals to take a more active role in their own health.
It is not surprising that the theme of personal empowerment is invoked. It’s great for marketing, but it’s not particularly empowering. In fact, if anything, it leaves patients even more reliant on authority, and it is not even very personal since the genetic contributions we know of are so small compared to how we actually live our lives. Then why is patient empowerment emphasized as a “cardinal virtue”? Because “it exploits the appeal…to generate political and public support” for an “increasingly industrialized medical-industrial and scientific complex, which moves trillions of dollars around the globe.”
This isn’t some grand conspiracy theory; it’s just the way the system works. “Healthy living directly threatens many powerful corporations….” Eat less sugar? Eat less meat? Healthier populations, after all, only reduce the demand for doctors and drugs. “Seemingly willfully blind to this evidence, the United States continues to spend its health dollars overwhelmingly on clinical care,” cleaning up our lifestyle-induced messes. So, it’s not surprising that we far outspend other countries while at the same time having worse outcomes. While major new taxpayer gifts were being promised to high-tech medicine about a decade ago, the United States had already sunk to the bottom among comparable countries with respect to disease experience and life expectancy. “Overrated ’precision medicine’ promises may be serving vested interests,…justifying the exorbitant healthcare expenditure in our finance-based medicine.” In lots of ways, the U.S. health care system is the most advanced in the world, but all our “whiz-bang technology just cannot fix what ails us.” “Let’s start with the basics. Eat your broccoli, take the stairs, and don’t worry about whether you have a 5.6 percent or 7.7 percent lifetime risk for a grave disease because either way, a sensible lifestyle is the healthiest choice.”
Doctor’s Note
The video I mentioned is Friday Favorites: How Useful Is Personalized Nutrition?.
