Direct-to-consumer pharmacogenomics tests: are they useful?

Image with science and DNA symbols
Pharmacogenomics (PGx) is the study of whether individual differences in how you express certain proteins or enzymes affect how your body processes certain drugs. This can translate into drugs working normally, drugs not working well, or you having excessive side effects.
Patients increasingly have access to direct-to-consumer genetic tests of all sorts. Companies such as Ancestry or 23andMe offer versions of PGx tests. But how are they different from what I offer patients through my business here at PharmDNA, LLC?
Many of the genes that are tested for in a PGx test yield results such as CYP2C19 *1/*1, where the “*1/*1” are referred to as “star alleles.” CYP2C19 is a very important gene, because it can give us critical information about effectiveness of medications such as Plavix, which is used after heart attack to prevent 2nd heart attacks! If this drug doesn’t work properly, patients can die (and have died).
Direct-to-consumer PGx tests, like 23andMe, only test for one or two of the most common “star alleles,” but there are DOZENS of possible star allele results for the CYP2C19 gene.
So what does this mean? It means that IF you happen to have the specific one or two versions of the gene that it tests for, it will most likely identify that and characterize your results correctly. BUT if you are among the rest of the population of patients that fall outside of those two versions of the gene, your result would be misclassified as “NORMAL” or “*1/*1” result.
For patients testing with me at PharmDNA, LLC, I use a clinical PGx test which covers several common and rare versions for this gene. This means a much greater likelihood of correctly identifying which “star alleles” you have, and what your true CYP2C19 metabolizer status is. The more variants that are tested for, the greater the likelihood of identifying problem variants and being able to use the clinical evidence to make useful recommendations to help patients!
This is also important because many ethnic groups have been shown to demonstrate similar PGx variants among certain genes. Testing for more rare variants allows us to personalize care for a more diverse patient population.
Another benefit of testing with me as a PGx consultant pharmacist is that I can perform a comprehensive look at your lifestyle factors, medications and your medical history. I can review all of these things that could possibly be affecting your medications, and make one-of-a-kind recommendations to improve your therapy! That’s something you’re not going to get from 23andMe!
Don’t let all of these genetic terms intimidate you! PGx can be complex. Even many physicians weren’t trained in it and are unfamiliar with the terms. This is why many of them don’t routinely order these tests– they might not even be aware they exist!
As a specialist in PGx, I aim to improve the adoption and implementation of PGx into clinical practice. I have personally seen the benefits for patients over and over! I’ve had dear friends and family members whose quality of life dramatically improved after I identified issues and made recommendations for how to address those. It is a very fulfilling way to be using my skills as a pharmacist!
I’m always thrilled to get questions about what I do, why I do it, and if PGx could benefit you. I’d love to hear from you!
Pharmacogenetics: Using Genetic Information to Guide Drug Therapy. Am Fam Physician 2015; 92(7):588-594.

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