rs13266634
The zinc transporter inside insulin granules
What this position does
Insulin is stored in the pancreas packed around zinc, and this transporter loads the zinc in. The variant version is associated with lower risk of type 2 diabetes. Unusually, rare mutations that break the gene completely are protective too, which is why it became a drug target.
Pancreas. Shaped by storing zinc with insulin. This is one of the variants that differs sharply between human populations, because something in the environment made one version worth having.
Insulin, and a food supply that changed
How much insulin the pancreas puts out, and when. These variants differ between populations and were mapped through type 2 diabetes, a disease that was rare before the food supply changed.
What changed: Industry, roughly the last two centuries. Indoor work, heated buildings, refined food, cheap salt and sugar, tobacco at scale, and a collapse in infectious disease. This is where most of the deals in your genome came undone.
Why it spread: nobody knows. The frequency difference between populations is real and measured. What the variant was worth having for is not known, and any site that tells you is guessing.
Spiral Staircase, chapter 13: The Thrifty Body Spiral Staircase is written by the same author as this site.
What each result means
| If you carry | What it means |
|---|---|
| No copies of the effect version CC | You have the higher-risk version on both copies The more common version in Europe, associated with a slightly higher risk of type 2 diabetes. |
| One copy CT | You carry one lower-risk copy Intermediate. |
| Two copies TT | You have the lower-risk version on both copies Associated with modestly lower type 2 diabetes risk. Common in East Asian and African populations. |
How common each version is
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 7.4% | |
| American | 26.7% | |
| East Asian | 45.7% | |
| European | 28.3% | |
| South Asian | 25.5% |
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.
How many people carry each result
| Ancestry group | CC | CT | TT |
|---|---|---|---|
| African | 566 / 661 | 92 / 661 | 3 / 661 |
| European | 262 / 503 | 197 / 503 | 44 / 503 |
| East Asian | 151 / 504 | 245 / 504 | 108 / 504 |
| South Asian | 270 / 489 | 189 / 489 | 30 / 489 |
| American | 186 / 347 | 137 / 347 | 24 / 347 |
Counts of people, not modelled frequencies: every one of the 2,504 individuals sequenced by the 1000 Genomes Project phase 3, tallied by the genotype they carry. Deriving these from allele frequencies instead would assume random mating inside each group and undercount the homozygotes.
How to find out which you have
If you have taken a test with 23andMe, AncestryDNA, MyHeritage, Family Tree DNA, TellMeGen or Living DNA, this position is very likely already in the raw data file they gave you. You do not need another test.
One thing to watch if you look it up by hand: testing companies report some positions from one DNA strand and some from the other, and the file does not say which. Read the letters as they appear and you will get the opposite of the truth for some positions. Sequencings resolves that automatically.
Source
Coordinates and allele pair verified against Ensembl GRCh37. Direction of effect verified against VEP protein consequences or 1000 Genomes population frequency. Category: Population adaptation.
Where this fits
Common questions
What is rs13266634?
rs13266634 is a position in the SLC30A8 gene on chromosome 8. Insulin is stored in the pancreas packed around zinc, and this transporter loads the zinc in. The variant version is associated with lower risk of type 2 diabetes. Unusually, rare mutations that break the gene completely are protective too, which is why it became a drug target.
What does it mean if I have TT at rs13266634?
You have the lower-risk version on both copies. Associated with modestly lower type 2 diabetes risk. Common in East Asian and African populations.
What does it mean if I have CC at rs13266634?
You have the higher-risk version on both copies. The more common version in Europe, associated with a slightly higher risk of type 2 diabetes.
How do I find out my rs13266634 genotype?
If you have taken a home DNA test, this position is very likely in the raw data file you were given. Sequencings reads that file in your browser without uploading it, and resolves which DNA strand each position was reported from, which is the step most manual lookups get wrong.
This is reference information, not medical advice, and not a diagnosis. See the medical disclaimer. Category: Population adaptation.