Markers / Gene
ACTN3
One position in this gene is readable from a home DNA test.
Fast-twitch muscle protein
rs1815739 · chr11:66,328,095 · C/T · evidence: strong
ACTN3 makes a structural protein found only in fast-twitch muscle fibres. Roughly a fifth of people carry two broken copies and make none of it at all, with no ill effect whatsoever.
| If you carry | What it means |
|---|---|
| No copies | Two working copies |
| One copy | One working copy |
| Two copies | No working copies |
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 11.5% | |
| American | 57.2% | |
| East Asian | 44.3% | |
| European | 43.4% | |
| South Asian | 58.7% |
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.
Read my file