Markers / Gene
CYP2C9
2 positions in this gene are readable from a home DNA test.
CYP2C9 *2
rs1799853 · chr10:96,702,047 · C/T · evidence: established
CYP2C9 clears warfarin, phenytoin and most anti-inflammatory painkillers. The *2 version works at reduced capacity.
| If you carry | What it means |
|---|---|
| No copies | No *2 copy |
| One copy | One *2 copy |
| Two copies | Two *2 copies |
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 0.8% | |
| American | 9.9% | |
| East Asian | 0.1% | |
| European | 12.4% | |
| South Asian | 3.5% |
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.
CYP2C9 *3
rs1057910 · chr10:96,741,053 · A/C · evidence: established
The more severe of the two common CYP2C9 variants, with a larger effect on warfarin dose than *2.
| If you carry | What it means |
|---|---|
| No copies | No *3 copy |
| One copy | One *3 copy |
| Two copies | Two *3 copies |
| Ancestry group | C (the effect version) | |
|---|---|---|
| African | 0.2% | |
| American | 3.7% | |
| East Asian | 3.4% | |
| European | 7.3% | |
| South Asian | 10.9% |
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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