GeneSight & Pharmacogenomics

GeneSight, Other Pharmacogenomic Tests and 23andMe: How They Differ

By Dr. Stacey Forbes, DNP, APRN, PMHNP-BC · Updated October 12, 2026

All pharmacogenomic tests look at genes that affect how your body handles medication, but they are not interchangeable. Clinical panels differ in which genes and variants they test and in how they present the result. Consumer DNA reports test far fewer variants and are designed to start a conversation, not to guide a prescription. This guide compares the main types factually, without ranking brands, and explains what to bring to a prescriber if you already have results from any of them.

Three kinds of “genetic medication test”

People use the same words for very different products. It helps to sort them into three groups before comparing anything.

The basic idea behind all of them is the same and is covered in genetics and psychiatric medication. The differences are in the details below.

Clinical panels: genes, variants and the way they report

Two clinical tests can both list CYP2D6 and still not be measuring the same thing. A gene has many known variants, and each lab chooses which ones its assay looks for. A joint recommendation from the Association for Molecular Pathology and the College of American Pathologists noted little consistency in the CYP2D6 variants included in clinical tests across laboratories, and set out a minimum list to improve that.

This matters in two specific ways:

• Untested variants are invisible. If you carry a rarer variant the assay does not include, the default result is a normal-function call. The report can look reassuring while missing something.
• Gene copies matter. Some people carry extra or missing copies of CYP2D6. The same recommendation calls detecting deletions and duplications an essential part of clinical CYP2D6 testing, because extra copies can push someone toward ultrarapid metabolism.

Then there is translation. A genotype is turned into a label such as “intermediate metabolizer” using a scoring method. A 2020 consensus from the Clinical Pharmacogenetics Implementation Consortium (CPIC) and the Dutch Pharmacogenetics Working Group found that methods differed between labs and guidelines, which could give the same genotype different labels. Under the shared method, people with a CYP2D6 activity score of 1.0, previously called normal metabolizers by CPIC, are now classed as intermediate.

How GeneSight presents its results

GeneSight’s current product page lists the genes in its psychotropic panel. Pharmacokinetic genes, which affect how the body breaks drugs down: CYP2D6, CYP3A4, CYP2B6, UGT1A4, CYP2C19, CES1A1, CYP1A2, UGT2B15 and CYP2C9. Pharmacodynamic genes, which relate to how a drug acts on the body: SLC6A4, HLA-A*3101, ADRA2A, HTR2A and HLA-B*1502. COMT is reported as informational only.

What sets the report apart in format is that it uses what the company calls a weighted multi-gene approach. Rather than giving you a separate verdict for each gene, it places more than 60 mental health medications into three groups: “Use as directed,” “Moderate gene-drug interaction” and “Significant gene-drug interaction.” The company is clear that the results are not a diagnosis and do not cover medication allergies, drug-drug interactions or which medication will work best.

Many other clinical panels take the opposite approach and report each gene’s genotype and metabolizer type, sometimes with drug-specific notes drawn from published guidelines. Neither format is “the right one.” A combined category is quick to scan; a gene-by-gene report shows its working and is easier to reinterpret if guidance changes. Some prescribers prefer one, some the other, and a good one can work with either.

Evidence for the pharmacodynamic genes is generally weaker than for the liver enzyme genes, a point covered in what the FDA and CPIC guidelines say.

Consumer reports: what the FDA authorized, and its limits

On 31 October 2018, the FDA authorized 23andMe’s Personal Genome Service Pharmacogenetic Reports, the first direct-to-consumer test of its kind, covering 33 variants in multiple genes. The FDA’s consumer test page lists genes such as CYP2C19, CYP2D6 and DPYD among them, for adults over 18.

The authorization came with unusually direct limits. In the FDA’s words, consumers “should not use this test to make treatment decisions on their own,” and results “should be confirmed with independent pharmacogenetic testing before making any medical decisions.” The report does not describe an association between the variants and any specific drug, and its labeling warns against using the results to stop or change medication.

At the same time, the FDA warned the public about pharmacogenetic tests making claims it had not reviewed. That warning applies to tests sold through clinicians as well as directly to consumers, and it is a good reason to ask any testing company what its claims are based on.

So a consumer report can be a reasonable prompt to ask, “Should I have clinical testing?” It is not a stand-in for that testing, and a prescriber will usually not change a psychiatric medication on its basis alone.

Raw data and third-party interpretation sites

Many consumer DNA services let you download a raw data file. Third-party websites offer to read that file and produce a pharmacogenomic report for a fee. MedlinePlus, from the National Library of Medicine, notes that these interpretation services have limited oversight, and that results from consumer testing typically need confirming through a healthcare professional.

There are practical problems too. The raw file comes from a chip designed for ancestry and wellness reports, so it may not include the variants a clinical assay would test, and it generally cannot detect extra gene copies. The third-party site cannot fix what the original data does not contain.

Privacy deserves a moment of thought as well. MedlinePlus warns that genetic privacy may be compromised if companies sell or share your data, and uploading a file to another company adds another privacy policy to read. The guide to genetic testing privacy and GINA explains what federal law does and does not protect.

Already tested? What to bring to your prescriber

If you have results from any test, clinical or consumer, they may spare you a second swab, or at least make the next decision easier. What helps most:

1. The full report, not a screenshot. The name of the laboratory, the date, and the list of genes and variants tested matter as much as the headline result.
2. The genotypes, if listed. Star-allele results (for example, a pair like *1/*4) let a clinician re-translate the result under current guidance. Labels alone cannot be updated.
3. Whether copy number was tested. For CYP2D6 this changes how much weight the result can carry.
4. Your full medication list. Other drugs and supplements can make you behave like a different metabolizer type than your genes suggest; see when other medications change your genetic result.

At Willow & Stone, an existing clinical report is reviewed like any other part of your history. Whether a new test is worth ordering depends on what the earlier one covered and on the decision in front of you, not on brand. If a new test does make sense, getting a GeneSight test, step by step covers the logistics.

Common Questions

Sources & Further Reading

• FDA — FDA authorizes first direct-to-consumer test for genetic variants that may be associated with medication metabolism (31 Oct 2018)
• FDA — Direct-to-Consumer Tests
• Pratt VM et al. Recommendations for clinical CYP2D6 genotyping allele selection (AMP/CAP). J Mol Diagn 2021
• Caudle KE et al. Standardizing CYP2D6 genotype to phenotype translation (CPIC/DPWG). Clin Transl Sci 2020
• MedlinePlus Genetics — Pros and cons of direct-to-consumer genetic testing
• GeneSight — GeneSight Psychotropic

This article is general education, not advice for your situation. Do not start, stop, or change a medication based on a genetic test result without talking to the clinician who prescribes it.