CYP2C19 in your raw data: how you metabolize certain drugs
CYP2C19 is one of the most clinically relevant things in your raw DNA, because it affects how you process several common medications. That also makes it one to handle carefully — raw consumer data is a starting point, not a prescription. Here's what CYP2C19 does, how to find it in your 23andMe or AncestryDNA file, and why any result belongs in a conversation with a professional.
This is educational information, not medical advice. Never start, stop, or change a medication based on raw data. Pharmacogenomic decisions need clinical-grade testing and a doctor or pharmacist.
What CYP2C19 does
CYP2C19 is a liver enzyme that breaks down a number of widely-used drugs, including:
- Clopidogrel (Plavix) — a blood thinner that actually needs CYP2C19 to activate it
- Proton-pump inhibitors (PPIs) — for acid reflux (omeprazole and similar)
- Some antidepressants (certain SSRIs) and other medications
How active your version is changes the drug levels in your body — which can mean too little effect or too much.
The metabolizer types
Your combination of CYP2C19 variants places you on a spectrum:
| Type | Activity | Key variants |
|---|---|---|
| Poor | Very low | Two loss-of-function alleles (e.g. *2 / rs4244285) |
| Intermediate | Reduced | One loss-of-function allele |
| Normal | Typical | Two normal (*1) alleles |
| Rapid / Ultrarapid | Increased | The *17 allele (rs12248560) |
The most consequential example: poor metabolizers don't activate clopidogrel well, so it may not protect them as expected — which is exactly why this gene is clinically tested before certain treatments.
How to find it in your raw data
- Download your raw data (or from AncestryDNA / MyHeritage).
- Search it for
rs4244285(the *2 loss-of-function variant) andrs12248560(the *17 increased-activity variant). - Or use our free DNA explorer to read the file in your browser.
Because CYP2C19 has real clinical weight and genotyping arrays can occasionally miscall a single position, never treat the raw-data readout as final.
What to do with the result
If you take — or are about to take — clopidogrel, a PPI long-term, or an affected antidepressant, your CYP2C19 status is genuinely useful to raise with your doctor or pharmacist, who can order proper pharmacogenomic testing. Acting on it is their job, not a raw-data lookup's.
For the rest of what your file holds, see our complete guide to analyzing 23andMe raw data, or browse the rest of the Quanome blog.
Find your markers privately, then talk to a professional
Quanome reads your raw DNA on your device and surfaces well-studied markers — without uploading your genome. For anything about medications, confirm with a doctor or pharmacist. Learn more about Quanome →
Frequently asked questions
What does CYP2C19 do?
CYP2C19 is a liver enzyme that metabolizes several important drugs, including the blood thinner clopidogrel (Plavix), proton-pump inhibitors (PPIs) for acid reflux, and some antidepressants. Variants change how fast you process these medications.
What are the CYP2C19 metabolizer types?
From slowest to fastest: poor, intermediate, normal, rapid, and ultrarapid metabolizers. Loss-of-function variants (like *2 / rs4244285) reduce activity; the *17 variant (rs12248560) increases it. Your combination of variants determines your type.
How do I find CYP2C19 in my 23andMe data?
Search your raw file for the key markers — rs4244285 (*2) and rs12248560 (*17) are the common ones. Because pharmacogenomics is clinically important and arrays can miscall single markers, treat raw-data results as a starting point only.
Can I change my medication based on raw data?
No. Never adjust or stop a medication based on consumer raw data. Pharmacogenomic decisions require clinical-grade testing and a doctor or pharmacist. This page is educational only.
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