Markers / Gene
SH2B3
One position in this gene is readable from a home DNA test.
One variant, coeliac disease, blood pressure and defence against bacteria
rs3184504 · chr12:111,884,608 · T/C · evidence: established
A striking example of one change doing several things at once. The same variant raises risk of coeliac disease, type 1 diabetes and higher blood pressure, and it also produces a stronger response to bacterial infection. The favoured explanation is that the infection benefit was worth the rest, in a world where infection killed you young.
| If you carry | What it means |
|---|---|
| No copies | You do not carry it |
| One copy | You carry one copy |
| Two copies | You carry two copies |
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 1.9% | |
| American | 25.4% | |
| East Asian | 0.3% | |
| European | 46.4% | |
| South Asian | 6.9% |
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.
Read my file