CYP2C9Your two copies: *1/*8
Intermediate metabolizer
One copy works and one works less well.
1.5 activity scoreTypical: 2Clears warfarin, phenytoin, celecoxib and some other pain relievers.
This result changes the label.
Example report. The whole genome example: a public genome from the 1000 Genomes Project, with CYP2D6 Structural Analysis, so you can see what yours will look like. Get your own report
Cardiovascular · Blood ThinnersExample report
Warfarin
Coumadin
Use with caution
Your genes suggest a lower dose may be safer. Your doctor can decide.
The genes behind this label
The guidelines read 3 genes for warfarin. Each card shows the two copies this person inherited and what they mean.
VKORC1Your two copies: -1639G/-1639G
GGNormal expression
Recycles vitamin K and is the protein warfarin blocks.
This result doesn't change the label.
CYP4F2Your two copies: *1/*2
Unable to determine
One copy (*1) works normally. The other (*2) has unknown function: research hasn't yet shown how well it works. So we can't say how well CYP4F2 works overall.
Clears extra vitamin K from the body, which changes how much warfarin you need.
No clear result for this gene (see above), so its part in the label is unknown.
What the guidelines say
What each guideline says about your result.
CYP2C9Intermediate metabolizerVKORC1Normal expressionCYP4F2Indeterminate
CPIC guideline, all three genes together
Evidence: strongRead the guideline (Clinical Pharmacogenetics Implementation Consortium, opens in a new tab)
Estimated dose: 3.5-6 mg/day (lower than typical starting dose).
- In plain words
- Your genes suggest a lower dose may be safer. Your doctor can decide.
Based on your CYP2C9 (*1/*8) and VKORC1 (-1639G/-1639G) genotypes, your predicted stable warfarin dose is 3.5-6 mg/day (decreased ~15-30% for CYP2C9 *5/*6/*8/*11). This estimate is genotype-based only and does not account for age, weight, or interacting drugs. A clinician should confirm the starting dose using a validated pharmacogenetic dosing algorithm.
Base genotype dose (CYP2C9 *1/*1, VKORC1 GG): 5-7 mg/day. Because you carry a CYP2C9 *5, *6, *8, or *11 reduced-function allele, your estimated dose is decreased by about 15-30%.
CPIC reads your CYP2C9, VKORC1 and CYP4F2 results together for warfarin, so this label reflects all of them.
How the dose estimate is worked out
The guideline starts from a dose table, then adjusts for other genes. Each step with this person's numbers:
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Start from the dose table
The FDA label's table gives a starting range from two genes. This VKORC1 result (normal expression) and CYP2C9 result (*1/*1) give 5-7 mg/day.
Starting dose by VKORC1 and CYP2C9, mg/day VKORC1 CYP2C9 *1/*1 CYP2C9 *1/*2 CYP2C9 *1/*3 CYP2C9 *2/*2 CYP2C9 *2/*3 CYP2C9 *3/*3 Normal expression (G/G) 5-7 (this result) 5-7 3-4 3-4 3-4 0.5-2 Decreased expression (G/A) 5-7 3-4 3-4 3-4 0.5-2 0.5-2 Low expression (A/A) 3-4 3-4 0.5-2 0.5-2 0.5-2 0.5-2 -
Adjust for CYP2C9 *5/*6/*8/*11: −15-30%
Because you carry a CYP2C9 *5, *6, *8, or *11 reduced-function allele, your estimated dose is decreased by about 15-30%.
- Low end
- 5 − 30% = 3.5 mg/day
- High end
- 7 − 15% = 6 mg/day
Estimated dose: 3.5-6 mg/day (lower than typical starting dose).
The table's starting dose with typical results is 5-7 mg/day.
This uses the FDA label's genotype table in place of the full CPIC dosing algorithm, which also weighs age, weight and other medicines. A clinician sets the actual dose.
About warfarin
Warfarin (Coumadin, Jantoven) is an oral anticoagulant used to prevent and treat blood clots.
- Used for
- Preventing and treating venous thrombosis and pulmonary embolism; preventing and treating clots linked to atrial fibrillation or a replaced heart valve; lowering the risk of death, another heart attack and clotting events such as stroke after a heart attack
Others in cardiovascular
Compare all 7 cardiovascularDon't change a dose on your own. Bring this report to your prescriber or pharmacist. They can weigh it with everything else they know about you.