rs762551
How fast you clear caffeine
What this position does
CYP1A2 does about ninety-five per cent of the work of breaking caffeine down. This position marks the faster and slower versions of the enzyme.
What each result means
| If you carry | What it means |
|---|---|
| No copies of the effect version AA | Fast metaboliser Two copies of the fast version. Caffeine clears relatively quickly, so a late coffee is less likely to cost you sleep. |
| One copy AC | Slower metaboliser One slow copy. Caffeine tends to linger, and the effect is larger in smokers because smoking induces the enzyme. |
| Two copies CC | Slow metaboliser Two slow copies. Caffeine clears slowly. Studies linking heavy coffee intake to heart risk have generally found the association only in this group. |
Worth knowing. Replication has been mixed and the enzyme is strongly induced by smoking and by some medicines, so behaviour moves this more than genotype does.
How common each version is
| Ancestry group | C (the effect version) | |
|---|---|---|
| African | 43.8% | |
| American | 24.2% | |
| East Asian | 32.7% | |
| European | 32.0% | |
| South Asian | 46.5% |
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 | AA | AC | CC |
|---|---|---|---|
| African | 213 / 661 | 317 / 661 | 131 / 661 |
| European | 239 / 503 | 206 / 503 | 58 / 503 |
| East Asian | 229 / 504 | 220 / 504 | 55 / 504 |
| South Asian | 145 / 489 | 233 / 489 | 111 / 489 |
| American | 205 / 347 | 116 / 347 | 26 / 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
Cornelis et al., Coffee, CYP1A2 genotype, and risk of myocardial infarction, JAMA (2006)
Coordinates and allele pair verified against Ensembl GRCh37. Direction of effect verified against VEP protein consequences or 1000 Genomes population frequency. Category: Trait.
Where this fits
Common questions
What is rs762551?
rs762551 is a position in the CYP1A2 gene on chromosome 15. CYP1A2 does about ninety-five per cent of the work of breaking caffeine down. This position marks the faster and slower versions of the enzyme.
What does it mean if I have CC at rs762551?
Slow metaboliser. Two slow copies. Caffeine clears slowly. Studies linking heavy coffee intake to heart risk have generally found the association only in this group.
What does it mean if I have AA at rs762551?
Fast metaboliser. Two copies of the fast version. Caffeine clears relatively quickly, so a late coffee is less likely to cost you sleep.
How do I find out my rs762551 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: Trait.