Written in partnership with Mental Health America

What is pharmacogenomics?

Pharmacogenomics (PGx), or pharmacogenetics, is the study of how a person’s genes influence their response to various drugs.

Your body metabolizes, or breaks down, medication over time. This happens mostly in the liver, with molecules called enzymes. Just six enzymes are responsible for metabolizing more than 90% of all psychiatric medications. Your DNA contains genes that tell your body how to make these enzymes.

Each of these genes has variations that lead to differences in enzyme structure and function. 

Just as differences in genes can lead to one person being blonde and another being a redhead, differences in this set of genes can lead to two people processing the same medication in different ways. 

What does a pharmacogenomics test do?

A PGx test looks at your DNA to see which version of each gene you have. 

Scientists often assign each variation to one of three groups: rapid metabolizer, slow metabolizer, and extensive metabolizer. These different groups correspond to whether your variation of a certain enzyme can break down a substance quickly, slowly, or at a normal rate, respectively. Knowing what kind of genetic variations you have gives your medical provider insight into how your body breaks down drugs. 

Doctors, including psychiatrists, have been increasingly using PGx testing in mental health treatment. It’s shown to reduce the risk of side effects, decrease medication switching, and, most importantly, increase the chance that their patients get better. 

How do PGx test results affect my prescription? 

PGx tests tell your medical provider how your genes differ from others—and how these differences affect your metabolism. Your PGx test tells you what version of each gene you have. It then provides a list of medications that are broken down by the enzyme that gene encodes. This list might also come with some recommendations.

For example, having a certain genetic variation might result in you having a slow metabolizer enzyme variant. Because this type of enzyme breaks down medication more slowly than average, a certain drug may stay in your system longer than usual. This can lead to negative side effects. A PGx test might recommend that your provider not prescribe this medication—or at least lower the dosage in order to prevent side effects. Without a PGx test, you would only find this out by trial and error.

What do scientists know about PGx tests?

 While pharmacogenetics may be an unfamiliar term to many, the term was first coined back in the 1950s. Since then, researchers have gained a greater and greater understanding about how specific genes impact the way in which we respond to different medications. Studies have shown that PGx testing can reduce the burden of side effects for people with major depressive disorder and improve outcomes in those with anxiety and depression. The FDA now recognizes the value of PGx tests, stating that they can be helpful in creating a prescription plan.

However, there is currently not enough knowledge on the relationship between genes and medication to definitively determine which medication is right for you and at which dosage. While genetics is a major factor, there are other things that affect the way you respond to medications. PGx tests can only provide recommendations and suggestions regarding various medications to reduce the trial and error approach to medication. Instead of providing an answer, PGx tests provide a starting point to help you and your provider to make the right decision about which medication is appropriate and in what amount.

PGx testing has the potential to shorten the trial-and-error period and help people more quickly find a plan that fits. If you’re wondering whether you are likely to benefit from pharmacogenetic testing, you can take a free pharmacogenomics quiz that’s backed by the latest scientific research.

Interested in learning about genetic testing? Read our post the genes examined in prairie’s genetic tests