rs1801394
The other folate gene, MTRR
What this position does
MTRR keeps the enzyme that recycles homocysteine back into methionine running, using vitamin B12. It is usually reported next to MTHFR, and it attracts some of the same overreach.
Folate cycle. Shaped by folate supply from a plant-heavy diet. This is one of the variants that differs sharply between human populations, because something in the environment made one version worth having.
What your ancestors ate
Fats, folate and the chemistry of plants. Populations that farmed, that fished, or that herded ended up building different enzymes for the same jobs.
What changed: Farming, the last 12,000 years. Grain, milk, settlement, crowds and the diseases crowds carry. Most of the adaptations a consumer chip can read are younger than this, which is why they still differ so sharply between populations.
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 4: The Last Ice Age and the Birth of Agriculture 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 AA | You have the common version on both copies Standard activity. |
| One copy AG | You carry one variant copy Slightly altered activity, with no established consequence for anyone eating an ordinary diet. |
| Two copies GG | You carry two variant copies The same, more so. As with MTHFR, the large clinical claims made for this gene are not supported by the evidence, and no supplement protocol should be built on it. |
How common each version is
| Ancestry group | G (the effect version) | |
|---|---|---|
| African | 24.6% | |
| American | 28.1% | |
| East Asian | 26.3% | |
| European | 52.3% | |
| South Asian | 52.5% |
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 | AG | GG |
|---|---|---|---|
| African | 374 / 661 | 249 / 661 | 38 / 661 |
| European | 129 / 503 | 222 / 503 | 152 / 503 |
| East Asian | 281 / 504 | 181 / 504 | 42 / 504 |
| South Asian | 106 / 489 | 253 / 489 | 130 / 489 |
| American | 184 / 347 | 131 / 347 | 32 / 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 rs1801394?
rs1801394 is a position in the MTRR gene on chromosome 5. MTRR keeps the enzyme that recycles homocysteine back into methionine running, using vitamin B12. It is usually reported next to MTHFR, and it attracts some of the same overreach.
What does it mean if I have GG at rs1801394?
You carry two variant copies. The same, more so. As with MTHFR, the large clinical claims made for this gene are not supported by the evidence, and no supplement protocol should be built on it.
What does it mean if I have AA at rs1801394?
You have the common version on both copies. Standard activity.
How do I find out my rs1801394 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.