"Should You Get Personalized Genetic Risk Testing?"
Today, you can get your DNA sequenced—the letters of your
entire genetic code spelled out— for like a thousand bucks,
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.
It’s only a click away, direct- to-consumer genetic testing
like 23andMe for ancestry, health, love—you name it.
Unfortunately, many tests currently offered have not been
appropriately validated, and consequently, the consumer
may be paying for something that is ultimately useless.
Or just flat out wrong.
There is an increasing demand from the public for
direct-to-consumer genetic tests, but when put to the test,
researchers found an alarmingly high false positive rate,
meaning the analysis said you had some high-risk gene,
but it simply wasn’t true.
And this happened 40 percent of the time!
Like they said you had the Angelina Jolie
BRCA breast cancer genes, but it wasn’t true.
And in addition to the 40 percent false positive rate,
some variants they 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 you scary outlier results, so you’ll think
the money was worth it and pay for additional testing.
But both false-positive results and misclassification of variants
can result in significant implications for an individual, including
unnecessary stress and even unnecessary medical procedures.
I mean, 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, these genome-wide association studies have now
successfully identified thousands of common genetic variants
that influence the risk of complex diseases,
as I talked about in my video on personalized nutrition.
But 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.
We’ve identified about 50 genes that are linked to
increased diabetes risk, but even if you put them all together,
“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 was 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 this 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, period.
But if you actually read the study, it turns out
their results do not demonstrate high interpersonal variation
in relative blood sugar responses;
do not show that their model is superior to current methods
of detecting high blood sugars;
and do not show that personalized nutrition advice is
superior to standard dietary advice to manage
high blood sugar responses after meals.
But what about personalized genetic risk counseling
just to at least motivate diabetes prevention?
In a somewhat forlorn bid to regain credibility,
"knowledge" of individual genetic risk proﬁles has been
touted as effective in motivating people to commit more
strenuously to relevant disease prevention efforts.
Here again, however, available evidence
does not support the claims.
And indeed, it did not seem to help those at risk for diabetes.
Randomize people to get genetic tests worth hundreds
or thousands of dollars profiling their subtle differences
in risk for up to 40 different diseases.
In this case, it was Navigenics who described their goal
as empowering people with personal genetic insights to help
motivate them to improve their health.
Yet, it didn’t work. No measurable changes
in diet or lifestyle, even in the short-term.
Randomize 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 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 of the studies together, and what do we find?
No significant benefits for telling smokers who’s
at particular risk for lung cancer for instance,
or who needs to eat particularly healthy, or move especially more.
The bottom line is that expectations that communicating
DNA-based risk estimates changes behavior are not supported
by existing evidence, yet that was the stated reason
for the big presidential push for precision medicine:
to empower individuals to take a more
active role in their own health.
It is no surprise 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’s not even very personal
since the genetic contributions we know of are so small
compared to how we actually live our lives.
Why, then, is patient empowerment
emphasized as it’s cardinal virtue?
Because it exploits the appeal to generate political
and public support for an increasingly industrialized
medical-industrial-scientific complex, which moves
literally 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?
And healthier populations do nothing
but lower the demand for doctors and drugs.
Seemingly willfully blind to this evidence,
the United States continues to overwhelmingly spend
its health dollars 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 have worse outcomes.
While major new taxpayer gifts were being promised
to high-tech medicine, the United States had already sunk
to the bottom of the list of comparable countries
in terms of disease experience and life expectancy.
“Overrated ’precision medicine’ promises may be serving
vested interests,…justifying the exorbitant healthcare
expenditure in our finance-based medicine.”
But in many ways, the American health care system is the
most advanced in the world, yet all our whiz-bang technology
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.”