Markers / Gene
CYP2C19
2 positions in this gene are readable from a home DNA test.
CYP2C19 *2, loss of function
rs4244285 · chr10:96,541,616 · G/A · evidence: established
CYP2C19 activates clopidogrel, a very widely used antiplatelet drug, and clears several antidepressants and stomach-acid drugs. The *2 version does not work at all.
| If you carry | What it means |
|---|---|
| No copies | No *2 copy |
| One copy | One *2 copy |
| Two copies | Two *2 copies |
| Ancestry group | A (the effect version) | |
|---|---|---|
| African | 17.0% | |
| American | 10.5% | |
| East Asian | 31.3% | |
| European | 14.5% | |
| South Asian | 35.8% |
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.
CYP2C19 *17, increased function
rs12248560 · chr10:96,521,657 · C/T · evidence: established
The opposite variant: a promoter change that makes more enzyme than usual.
| If you carry | What it means |
|---|---|
| No copies | No *17 copy |
| One copy | One *17 copy |
| Two copies | Two *17 copies |
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 23.5% | |
| American | 12.0% | |
| East Asian | 1.5% | |
| European | 22.4% | |
| South Asian | 13.6% |
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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