Pharmacogenomics in context
The Triangle is home to major pharmaceutical companies, contract research organizations, and leading academic medical centers, so many patients already know the basics of pharmacogenomics. GeneSight, from Myriad Genetics, is a commercial combinatorial pharmacogenomic test that analyzes genes relevant to many psychiatric medicines.
Genes analyzed
The panel includes pharmacokinetic genes such as CYP2D6, CYP2C19, CYP2C9, CYP3A4, CYP1A2, and CYP2B6, which affect drug metabolism, and pharmacodynamic genes related to serotonin and other targets. Metabolizer status, from poor to ultrarapid, can change drug exposure substantially.
The combinatorial report
Rather than listing genotypes alone, GeneSight combines results into three categories for each medicine: use as directed, moderate gene-drug interaction, and significant gene-drug interaction. Your provider can also review the underlying genotypes if you are interested.
Appropriate use
Testing is most informative after two or more failed antidepressant or anxiolytic trials, with unusual side effects at standard doses, or with polypharmacy. For treatment-naive patients, standard first-line choices are usually reasonable without testing.
The evidence
The GUIDED randomized controlled trial reported higher response and remission rates with GeneSight-guided treatment, while the primary endpoint of symptom improvement did not reach statistical significance. CPIC guidelines provide gene-based dosing recommendations for several SSRIs and tricyclics using CYP2D6 and CYP2C19 status. The FDA has not approved GeneSight for selecting antidepressants. Testing refines probability; it does not determine outcome.
Limitations
Phenoconversion matters: strong CYP2D6 inhibitors like bupropion, fluoxetine, and paroxetine can make a normal metabolizer behave like a poor one. Smoking induces CYP1A2. Your provider interprets results in light of current medicines and habits, alongside a full psychiatric evaluation.
Clinical trial participants
If you are enrolled in a drug study, mention it. Some trials collect their own genetic data, and investigational medicines can interact with psychiatric treatment.
Integrating results with your care team
With your consent, results can be shared with your primary care physician, cardiologist, or pain specialist, since CYP2D6 and CYP2C19 also affect many non-psychiatric medicines, including codeine, tramadol, clopidogrel, and some beta blockers.
Privacy and GINA
Results are part of your protected health record. The Genetic Information Nondiscrimination Act of 2008 restricts most employers from using genetic information in employment decisions.
A worked example
Consider a postdoc who had no response to escitalopram at a full dose and marked nausea on sertraline. A report might show CYP2C19 ultrarapid metabolism, which can lower escitalopram exposure, and guideline-based advice to consider an agent not primarily metabolized by CYP2C19. The report informs the choice; the decision remains clinical and shared.
Interpreting a reassuring result
A report with most medicines in the use-as-directed group is still informative: it suggests past failures were less likely due to metabolism, which shifts attention to diagnosis, dose adequacy, duration, adherence, or comorbidity.
When to defer testing
If you have tried only one medicine briefly, an adequate trial at a full dose usually comes first. Your provider will be candid about whether testing would change management now.
Questions to bring
Which medicines are under consideration next? How would each possible result change the ranking? Are current medicines likely to cause phenoconversion?
Process
You and your provider decide whether results could change management. A buccal swab is collected at either office. Your provider reviews the report with you and discusses implications.
Durable results
Germline results do not change, so the report remains useful for future decisions and can be shared with other prescribers with your consent.
When a result changes nothing
Sometimes a report confirms that the medicines already working for you are well matched. That is useful too: it can spare you an unnecessary switch and give you confidence in the current plan.
Family history
If a relative responded unusually to a psychiatric medicine, mention it. Genotypes are individual, but family patterns can prompt useful questions.
Getting started
Testing is ordered within your care here and integrated into medication management. Visit 2530 Meridian Pkwy in Durham or 9121 Anson Way in Raleigh. Become a patient to discuss whether it fits.
Why Choose Triangle Psychiatry and Mental Health?
- Board-certified psychiatric providers serving Durham and the Triangle area
- Research-backed treatment protocols
- Full documentation for all evaluations
- Coordinated care with your other providers across the region