An evidence-minded approach
Boulder patients often arrive with questions about mechanisms and studies. That is a good fit for GeneSight, a pharmacogenomic test from Myriad Genetics that analyzes genes involved in how your body processes and responds to many psychiatric medicines. Your provider will walk through what it can and cannot tell you before you decide.
How pharmacogenomics works
Pharmacokinetic genes, mostly in the cytochrome P450 family such as CYP2D6, CYP2C19, CYP2C9, CYP3A4, and CYP1A2, determine how quickly enzymes metabolize drugs. Pharmacodynamic genes, such as those related to serotonin receptors, may influence how a drug acts in the brain. Variations can make you a poor, intermediate, normal, rapid, or ultrarapid metabolizer for certain medicines.
Reading the report
Medicines are sorted into three groups based on predicted gene-drug interactions: use as directed, moderate, and significant. The report is a guide, not a rulebook. Your provider weighs it with your history, side effects, preferences, and other health conditions.
When testing is worth it
Testing is most likely to change decisions when:
- Two or more antidepressants or anxiety medicines have failed
- Normal doses caused unusual side effects
- You take several medicines and interactions are a worry
- Relatives had unusual responses to psychiatric medicines
For a first medicine trial, testing usually adds little.
What the research says
In the GUIDED randomized trial, patients whose treatment was informed by GeneSight showed higher response and remission rates, though the primary endpoint of symptom improvement did not reach statistical significance. Separately, the Clinical Pharmacogenetics Implementation Consortium (CPIC) publishes peer-reviewed guidelines for adjusting several antidepressants based on CYP2D6 and CYP2C19 status. In short, testing can improve the odds, but it is not a guarantee.
Limits worth knowing
The test does not diagnose any condition and cannot predict with certainty which medicine will work. Smoking, other medicines, and some supplements can shift enzyme activity regardless of genes. The FDA has not approved GeneSight to choose antidepressants. Your provider uses it as one input alongside a full psychiatric evaluation.
Supplements and interactions
St. John's wort strongly induces CYP3A4 and other enzymes, and grapefruit can inhibit CYP3A4. These effects can matter as much as genetics. Bring your supplement list so your provider can read your results in context.
The process
You and your provider discuss whether results are likely to change your plan. A cheek swab is collected and mailed to the lab. Your provider reviews the report with you and explains how it affects your options.
A worked example
Suppose a grad student took escitalopram at a full dose for two months with no benefit. A report might show she is an ultrarapid CYP2C19 metabolizer, which can clear escitalopram before it reaches a helpful level. Expert guidelines suggest considering a medicine not mainly processed by that enzyme. The report informs, and your provider decides with you.
Genetic privacy
Results are part of your protected health record. The federal Genetic Information Nondiscrimination Act of 2008 prohibits most employers from using genetic information in employment decisions.
Questions to bring
Ask which medicines are on the table next, how results could change the order, and what your provider would do if the test came back normal. It also helps to mention any relative who did unusually well or poorly on a psychiatric medicine, since family experience and genetic results together give a clearer starting point.
When testing can wait
If you have only tried one medicine for a few weeks, a full trial at the right dose usually comes first. Your provider will be candid about whether results are likely to change your next step, and will not order a test that will not help.
Long-term value
Because your genes do not change, the report remains useful for future decisions. With your consent, it can be shared with other doctors who prescribe medicines for pain, heart conditions, or reflux, many of which use the same enzymes.
Getting started
Testing is ordered within your care here and followed through medication management. Visit 1434 Spruce St in Boulder. Become a patient to ask whether it fits your situation.
Why Choose Flatirons Psychiatry and Mental Health?
- Board-certified psychiatric providers serving the Boulder area and all of Colorado
- Research-backed treatment protocols
- Full documentation for all evaluations
- Coordinated care with your other providers across the region