Markers / Gene
CYP4F2
One position in this gene is readable from a home DNA test.
CYP4F2 and warfarin dose
rs2108622 · chr19:15,990,431 · C/T · evidence: established
The third gene in the standard warfarin dosing algorithm, after CYP2C9 and VKORC1. It affects vitamin K turnover, so carriers need slightly more warfarin.
| If you carry | What it means |
|---|---|
| No copies | You do not carry it, so standard warfarin dosing applies |
| One copy | One copy, so slightly more warfarin is typically needed |
| Two copies | Two copies, so around ten per cent more warfarin is typically needed |
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 8.2% | |
| American | 23.8% | |
| East Asian | 21.4% | |
| European | 29.0% | |
| South Asian | 41.3% |
1000 Genomes Project phase 3, via Ensembl, retrieved 2026-09-23. These groupings are coarse and flatten a great deal of internal diversity, particularly within Africa. A variant being common somewhere tells you where a piece of your ancestry probably comes from, and nothing else.
Where this gene fits
If you have taken a home DNA test, these positions are already in your file.
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