rs2187668
Coeliac disease risk type
What this position does
Coeliac disease requires a specific immune receptor type to be possible at all. This position tags the main one, HLA-DQ2.5. Its real value is the negative: without a permitting type, coeliac disease is very nearly ruled out.
What each result means
| If you carry | What it means |
|---|---|
| No copies of the effect version CC | DQ2.5 not detected This tag is absent. That removes the main risk type but not the second one, DQ8, which this position does not cover. |
| One copy CT | DQ2.5 present, one copy You carry a permitting type. So do roughly a quarter to a third of Europeans, and the large majority never develop coeliac disease. |
| Two copies TT | DQ2.5 present, two copies Two copies carry a higher risk than one. It remains a permitting condition rather than a prediction. |
Worth knowing. A tag, not the gene itself. Never start or stop a gluten-free diet on this result: testing for coeliac disease requires you to be eating gluten at the time, so going gluten-free first makes the real diagnosis much harder.
How common each version is
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 5.4% | |
| American | 11.8% | |
| East Asian | 5.2% | |
| European | 10.6% | |
| South Asian | 7.9% |
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.
How many people carry each result
| Ancestry group | CC | CT | TT |
|---|---|---|---|
| African | 592 / 661 | 67 / 661 | 2 / 661 |
| European | 401 / 503 | 97 / 503 | 5 / 503 |
| East Asian | 452 / 504 | 52 / 504 | 0 / 504 |
| South Asian | 419 / 489 | 63 / 489 | 7 / 489 |
| American | 275 / 347 | 62 / 347 | 10 / 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: Health-adjacent.
Where this fits
Common questions
What is rs2187668?
rs2187668 is a position in the HLA-DQA1 gene on chromosome 6. Coeliac disease requires a specific immune receptor type to be possible at all. This position tags the main one, HLA-DQ2.5. Its real value is the negative: without a permitting type, coeliac disease is very nearly ruled out.
What does it mean if I have TT at rs2187668?
DQ2.5 present, two copies. Two copies carry a higher risk than one. It remains a permitting condition rather than a prediction.
What does it mean if I have CC at rs2187668?
DQ2.5 not detected. This tag is absent. That removes the main risk type but not the second one, DQ8, which this position does not cover.
How do I find out my rs2187668 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: Health-adjacent.