{{Rsnum
|rsid=2287780
|Gene=MTRR
|Chromosome=5
|position=7889191
|Orientation=plus
|GMAF=0.07622
|Gene_s=MTRR
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
}}{{ population diversity
| geno1=(C;C)
| geno2=(C;T)
| geno3=(T;T)
| CEU | 94.7 | 5.3 | 0.0
| HCB | 72.1 | 26.5 | 1.5
| JPT | 69.6 | 25.9 | 4.5
| YRI | 98.0 | 2.0 | 0.0
| ASW | 96.5 | 3.5 | 0.0
| CHB | 72.1 | 26.5 | 1.5
| CHD | 72.5 | 24.8 | 2.8
| GIH | 92.1 | 7.9 | 0.0
| LWK | 90.0 | 10.0 | 0.0
| MEX | 62.1 | 37.9 | 0.0
| MKK | 91.7 | 8.3 | 0.0
| TSI | 99.0 | 1.0 | 0.0
| HapMapRevision=28
}}[[Yasko Methylation]] Methionine synthase, coded by the MTR gene, has a B12 attached to it. The Methionine synthase takes a methyl group from methyl folate and attaches it to its B12, then it attaches it to a molecule of homocysteine, turning it into methionine, which in turn becomes SAMe. After 1000-2000 times doing this, the B12 gets turned into a useless form, and MTRR turns the B12 back into the useful form so that the molecule of MTR can keep working. The MTRR mutations make this enzyme less active, suggesting a need for more B12.

{{PMID Auto
|PMID=20445798
|Title=Chromosome 5p Region SNPs Are Associated with Risk of NSCLC among Women.
|OA=1
}}

{{on chip | 23andMe v1}}
{{on chip | 23andMe v2}}
{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}
{{on chip | FTDNA2}}
{{on chip | FTDNA}}
{{on chip | HumanOmni1Quad}}
{{on chip | Illumina Human 1M}}