Markers / Gene
TCF7L2
One position in this gene is readable from a home DNA test.
Type 2 diabetes, the strongest common variant
rs7903146 · chr10:114,758,349 · C/T · evidence: established
Of the hundreds of common variants linked to type 2 diabetes, this one has by far the largest effect and has replicated in essentially every population studied. It appears to act on insulin secretion rather than on insulin resistance.
| If you carry | What it means |
|---|---|
| No copies | You have the lower-risk version on both copies |
| One copy | One higher-risk copy, roughly 1.4 times the background risk |
| Two copies | Two higher-risk copies, roughly twice the background risk |
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 26.0% | |
| American | 23.5% | |
| East Asian | 2.3% | |
| European | 31.7% | |
| South Asian | 29.9% |
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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