CYP2R1: the vitamin-D activation gene
Two genes can leave you short on vitamin D. This one runs the switch that turns it on.
Vitamin D does almost nothing until your body switches it on, and your liver runs the first step. CYP2R1 makes the enzyme that does that conversion. One common version of the gene, rs10741657, keeps turning up in people who run low on vitamin D and slip into deficiency more often.
What CYP2R1 does
Same honest read as the GC variant: your genes nudge your starting point lower, not how well you respond to a supplement. So the play doesn't change. Get your level checked, and if you're short, take D3 with K2.
Carry this one and the GC variant together and the odds of running low stack up. Good reason to actually measure a 25(OH)D level instead of guessing.
Your variants, decoded
The G allele tracks with lower 25(OH)D and a higher shot at deficiency. Reading note: this site is reported here on the forward strand (alleles A and G). A 23andMe or AncestryDNA export may print the complementary letters T and C instead, where C lines up with G (the lower-vitamin-D version) and T with A. Match by the variant, not the exact letter.
| AA | Typical vitamin-D activation. |
| AG | One copy. Levels tend to run a bit lower. |
| GG | Two copies. Lowest of the three, and the genotype where a blood test earns its keep most. |
We show genotypes on the forward strand and ignore letter order. Your own export may print the complementary letters. Same result either way.
What the research suggests
Your CYP2R1 rs10741657 G allele tracks with lower circulating vitamin D and a higher chance of running deficient, so it's worth testing your level and thinking about D3. One thing to be clear on: the vitamin-D benefit is GENERAL, the same for anyone. It's not unique to your genotype. Your genes raise the odds you're starting low, not how you respond to the supplement.
PubMed 30120973 · CYP2R1 rs10741657 & 25(OH)D / deficiency risk
Educational only, not medical advice. “General evidence” means the finding is real, but the benefit isn’t specific to your genotype.
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Questions
What does CYP2R1 do for vitamin D?
It runs the first step that turns vitamin D into the form your body can use. One common version of the gene tracks with lower blood levels and a higher chance of deficiency.