Markers / Gene
VKORC1
One position in this gene is readable from a home DNA test.
Warfarin sensitivity, VKORC1
rs9923231 · chr16:31,107,689 · C/T · evidence: established
VKORC1 is warfarin's actual target. This promoter variant lowers how much of the target is made, so less warfarin is needed. Together with CYP2C9 it explains a large part of why the required dose varies so widely between people.
| If you carry | What it means |
|---|---|
| No copies | Standard sensitivity |
| One copy | Increased sensitivity |
| Two copies | High sensitivity |
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 5.4% | |
| American | 41.1% | |
| East Asian | 88.5% | |
| European | 38.8% | |
| South Asian | 14.5% |
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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