The overhyped “precision medicine” may only serve vested interests, and consumer DNA testing may be useless, or worse.
DNA sequencing (detailing the letters in the entire genetic code) can now be done for about $1,000, compared to the $100 million or so it cost 20 years ago. And for about $100, partial DNA sequencing is possible. Direct-to-consumer genetic tests like 23andMe allow you to test for “ancestry, health, love, and more” with “just a click.” Unfortunately, many of the currently available tests have not been properly validated. And as a result, buyers may end up buying something that is “ultimately useless.” Or the results could be completely wrong.
There is growing public demand for direct-to-consumer genetic tests, but researchers found an “alarmingly high false-positive rate” when conducting the tests. Test results showed that people had high-risk genes, but that wasn’t true at all. And this specifically happened with the BRCA breast cancer gene (which Angelina Jolie publicly revealed she carries) 40% of the time. You can see this below and at 1:08 of my video “Should I Get an Individualized Genetic Risk Test?”In addition to the 40% false-positive rate, some variants that the test correctly identified were misclassified as high-risk when they were actually not high-risk at all. You can see how it is profitable for these companies to give horrible outlier results. Therefore, customers may think it was worth the money spent and may even pay for additional testing. However, false-positive results and misclassification of variants can have serious human consequences, including unnecessary stress and unnecessary medical procedures. What if you don’t even have a BRCA mutation, but mistakenly think you’re at high risk and undergo a preventive double mastectomy?
Yes, as we talked about in our video on personalized nutrition, these genome-wide association studies have identified thousands of common genetic variations that influence risk for complex diseases. “Nonetheless, the discovered genetic variants do not significantly extend our predictive power compared to what could be achieved using only information from long-known traditional risk factors.”
Let’s take type 2 diabetes as an example. Researchers have identified about 50 genes associated with increased risk of diabetes, but taken together, “obese people with the lowest genetic risk for diabetes were nearly five times more likely to develop diabetes than normal-weight people with the highest genetic risk.” In other words, this sends the wrong message to obese people and gives them a false sense of security. Knowledge of genetic susceptibility to type 2 diabetes, based on what we know so far, “does not influence decisions about who should be targeted for intensive lifestyle interventions.” Anyone with excess body fat, regardless of genetics, needs to lose weight to reduce their risk of diabetes.
What about the famous study that purports to show that personalized dietary interventions can improve blood sugar response? Some commentators say they question the usefulness of universal dietary recommendations. However, when you actually read this study, the results show that there is no significant interpersonal variation in relative blood sugar responses. This model has not been shown to be superior to current methods of detecting hyperglycemia. Additionally, we have not shown that personalized nutritional advice is superior to standard dietary advice for managing postprandial hyperglycemic responses.
But what about personalized genetic risk counseling, at least to motivate diabetes prevention? “In a rather half-hearted attempt to restore trust, ‘knowledge’ of an individual’s genetic risk profile has been touted as effective in motivating those who test positive to be more diligent in prevention efforts for associated diseases…” But again, the available evidence does not support that claim. And in fact, it appears to have no effect on people at risk for diabetes.
Researchers randomly assigned people to undergo genetic tests worth hundreds or thousands of dollars, revealing subtle differences in risk for up to 40 diseases. In this case, it was Navigenics that described its goal as empowering people with personal genetic insights and helping motivate them to improve their health. Still, it didn’t work. There were no measurable changes in diet or lifestyle, even in the short term.
Randomizing people to get personalized nutritional insights is like deciding who is genetically likely to particularly benefit from eating more vegetables or eating to lower cholesterol, but when researchers tested them, there were no significant changes in their diets in month 6 compared to people who didn’t get that personalized information, or even in month 3. So it’s no surprise that there were no differences in weight, abdominal fat, cholesterol, or other biomarkers.
What do we know when we put all the research together? There’s no great benefit to telling smokers who is at particular risk of developing lung cancer, who needs to eat an especially healthy diet, and who needs to be more physically active. Conclusion: The expectation that awareness of DNA-based risk estimates will change behavior is not supported by existing evidence. But the reason the president made a big push for precision medicine in 2015 was to empower individuals to take a more active role in their own health.
It’s no surprise that the theme of personal empowerment comes up. Great for marketing, but not particularly empowering. In fact, if anything, it makes patients even more dependent on authority, and it’s less personal because the genetic contributions we know about are so small compared to how we actually live. So why is patient empowerment emphasized as a “fundamental virtue”? Because it is “exploiting its appeal to generate political and public support” for “an increasingly industrialized medical-industrial-scientific complex that moves trillions of dollars around the world”.
This isn’t some grand conspiracy theory. It’s just the way the system works. “Healthy living directly threatens many powerful companies…” Would you like to eat less sugar? Would you like to eat less meat? After all, a healthier population will only reduce the demand for doctors and drugs. “Despite what appears to be a willful disregard for this evidence, the United States continues to spend overwhelmingly its health care dollars on clinical care,” shedding light on the confusion caused by our lifestyles. So it’s no surprise that our country spends much more than other countries, while at the same time producing worse outcomes. About a decade ago, with the promise of large new taxpayer dollars for high-tech medicine, the United States was already at the bottom of peer countries in terms of disease experience and life expectancy. “The overhyped promise of ‘precision medicine’ may be serving vested interests and justifying exorbitant medical costs in fiscally driven medicine.” Although the U.S. health care system is in many ways the most advanced in the world, “breakthrough technology cannot solve what ails us.” “Start with the basics: Eat your broccoli, take the stairs, and don’t worry about whether your lifetime risk of serious illness is 5.6 percent or 7.7 percent, because either way, a smart lifestyle is the healthiest choice.”
doctor’s note
The video I mentioned is “Friday Favorites: How Useful Is Personalized Nutrition?”
