#392 - Genetic testing: when it's valuable, how to choose the right test, and what to do with the results

**Peter Attia** (0:11)
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Welcome to today's episode of The Drive. Few areas in medicine generate as much fascination and as much confusion as genetic testing. The basic intuition here is sound. If DNA contributes so strongly to our biological machinery, then sequencing, it should in principle help us understand health and disease more clearly. It's true that some genetic tests can be genuinely life-changing, but it's equally true that others are barely more useful than a horoscope.
Most fall somewhere in between, in a gray zone that is far more nuanced than either the hype or the skepticism would suggest. So today, I want to build a practical framework for thinking clearly about genetic testing. Through this, I'll discuss what genetic tests can and can't do, why most genetic tests are probabilistic rather than deterministic, and why directly measuring the phenotype is often more useful than inferring risk from DNA alone. I'll also walk through where genetics can be most informative across the major disease categories, the four horsemen, and where it is much more limited than people assume. Finally, I'll talk about how to choose the right test or type of test, how to interpret the results and how to avoid the very common mistake of getting more information without getting more clarity. So without further delay, I hope you enjoy this episode of The Drive.
Recently, a patient asked me a question that I hear all the time. Should I be doing genetic testing? It sounds like a simple question, but in reality, it doesn't tell me very much. Because the question can mean a lot of different things. It could mean I'm worried about my risk of Alzheimer's disease should be test for ApoE genotype. It could mean my mother died of breast cancer. Should I find out whether or not I carry a BRCA mutation? It could mean, will genetic testing help determine the best medication to address my lipids? Or more commonly, it means something much broader. What diseases am I most likely to get? And that last question is really what most people have in mind. And I, of course, understand why. The notion that your DNA might serve as the kind of blueprint for your future health, that if you could read it closely enough, it would tell you what problems are coming and what to do about them, that is an extraordinarily compelling idea. If we truly had a test that could reliably tell you which diseases you were most likely to develop and exactly how to prevent them, that would be a genuine game changer for medicine. And that promise, or at least some version of that promise, is what many companies have tried to sell. Genetic testing has been marketed as a way to tell you everything, from what diet you should eat, to how you should exercise, to which supplements you need, to how well your body handles things like detoxification or methylation. But this is where we have to slow down and be much more precise, because that's not quite the reality we live in. Genetic testing can absolutely be useful. In some cases, it can be very useful, even life altering. There are situations where it can meaningfully change screening, influence treatment decisions, clarify risk or provide critical information for family members. But there are also many situations where it adds very little, where it's oversold or where the better answers come not from genetics at all, but from directly measuring the phenotype through blood work, imaging, family history, or other clinical evaluation. So the real question is not simply, should I do genetic testing? The real questions are, what exactly am I trying to learn and is genetic testing the best tool to answer that? If so, what kind of test is actually appropriate? And if I get an answer, will it change anything meaningful about what I do next? That's how I'd like to approach this discussion today.