MTHFR & Methylation: How to check your 23andMe results

It is easy to check your 23andMe results for the two main MTHFR variants:

Check your 23andMe results for rs1801133 for the MTHFR C677T:

  • GG: normal (wildtype)
  • AG: one copy of C677T allele (heterozygous), MTHFR efficiency reduced by 40%
  • AA: two copies of C677T (homozygous), MTHFR efficiency reduced by 70 – 80%


Check your 23andMe results for rs1801131 for the MTHFR A1298C:

  • TT: normal (wildtype)
  • GT: one copy of A1298C allele (heterozygous), MTHFR efficiency reduced
  • GG: two copies of A1298C (homozygous), MTHFR efficiency reduced


 Here is what the MTHFR gene does:

There is a lot of swirl on the internet about MTHFR with people thinking it is the cause of everything under the sun. This seems to have caused a bit of a backlash with doctors claiming that MTHFR variants are completely unimportant.

Let’s take a look at a bit of the science:

The methylation pathway is a central biochemical process that impacts all of our cells. Methylation is the adding and removing of a methyl group (CH3) to amino acids, DNA, and other enzymes or proteins. Methylation turns on and off genes, maintaining and repairing your DNA, as well as altering proteins. It is important in the nervous system in the production and breakdown of neurotransmitters.

The methylation cycle is involved with homocysteine, cholesterol, and other important players in heart disease, and genetic variants in the methylation pathway have been linked to heart disease. Additionally, the pathway is involved in regulating hormones such as estrogen, as well as playing a role in histamine levels.

Genetic variants can change how well a piece of the methylation pathway works.  Knowing where you have genetic variations can help you understand what you need to do to get around the slow-downs in the methylation pathway.

MTHFR is a central gene in the methylation cycle; common genetic variants in the coding of this gene affect more than half the population. Specifically, the MTHFR(methylenetetrahydrofolate reductase) gene codes for an enzyme that turns folate (think leafy greens) into the active form, 5-methyltetrahydrofolate, that your body uses. This, along with the active form of vitamin B-12  (methylcobalamin) drives an important portion of the methylation cycle.

Variations in the MTHFR gene have been linked to an increased risk of higher homocysteine, neural tube defects, spina bifida, heart disease, stroke, preeclampsia, and several psychiatric disorders. [ref]

The very extensive research shows, though, that MTHFR variants are linked to an increased risk for the disorders listed above. The increase in risk, though, isn’t a huge increase for most diseases. Thus, optimizing your methylation cycle can be important to your overall health, but probably isn’t the smoking gun for every ailment under the sun.


What should you do about an MTHFR mutation?  First off, start reading and educate yourself! There is a lot more to the methylation cycle than just the MTHFR gene.

Increasing your intake of folate from foods will help mitigate some of the risks from the MTHFR variant.  Foods containing folate include leafy greens, lentils, asparagus, and broccoli.  Note that when you are looking at folate content, you need to make sure it isn’t folic acid (synthetic form in processed foods) if you have methylation cycle variations. Here is a good list of food sources of folate.

If you aren’t getting enough folate from foods, you could try a low-dose methyl folate supplement.

Go and get your homocysteine level checked.  High homocysteine levels have been linked to risk of heart disease, and methyl folate plus B12 may help reduce your homocysteine.  In the US, you can order this online without a trip to the doctor through Walk-In Labs or other testing providers.

More to read about methylation cycle variants:

General MTHFR and Methylation cycle information:


updated 12/2017

12 Replies to “MTHFR & Methylation: How to check your 23andMe results”

  1. I contacted 23andme with some questions and now they deny tracking MTHFR genes any longer. If this is in response to MTHFR’s interest I’m not sure… I suppose it could just be customer service not knowing what they’re talking about. From what you know about their process can you verify? Would they just stop tracking certain genes or not? From their website, they only give a handful of terribly brief reports now and not the detailed genetic details this website seems to imply.
    Any light you could shine on this would be greatly appreciated.

    1. Hi,
      As far as I know, the raw data file still contains the data for the two most looked at MTHFR variants. 23andMe doesn’t include MTHFR in their health reports, which could be what the customer support response meant. I’ve found that getting answers from their customer support is sometimes difficult in that they send answers that seem scripted.
      The health reports on the 23andMe website are ones that the FDA has approved for them to present to their customers. What most people look at – from 23andMe, AncestryDNA, etc – is the raw data file (contains about 600,000 SNPs).

  2. Thanks Debbie. It seems they try to move everyone through the “Browse Raw Data” feature, which contains a limited number of SNPs, but your explanation and from what I’m able to see about the raw data file, which is still available, makes sense and is what I’m looking for. Thanks again!

  3. There’s a lot more to methylation than 1 gene, and the majority of the population, I believe it’s 80% or so have one variant in the two listed. Although these genes are important, they work synergistically with MANY other genes, some that could be wayyy more important in the long run. For most, if not all, there are many gene variants at need to be worked out prior to MTHFR. If the others aren’t functioning than of course you will have an issue with methylation and your varied MTHFR.
    I know you mentioned that there is a lot more to it but I commented because this issue is SO vital for people to understand. 5 or so years ago when I found out I was heterozygous for both MTHFR genes mentioned I thought that was the end all be all and I just needed to supplement—and so did every practitioner under the sun. BIG MISTAKE!! I cringe when I see suggestions that say to try certain supplements with such little information, because it can cause devastating consequences. Coming from someone who had a habit of playing her own doctor over here! Please please PLEASE educate yourselves people, and start working with a Doctor well versed in methylgenetic nutrition. An MD or ND that knows more than the bare minimum—which can actually be somewhat hard to find. Best of luck~ and more so education, perseverance and dedication to all who read this!
    In health,
    Becky :)

    1. I completely agree that there is more just MTHFR to learn about, and I would add that there is a lot more than just methylation cycle genes. So much more that I’ve written 100+ articles on this website about other genetic variants that impact our lives :-) I encourage you, and everyone else, to keep reading and keep learning.

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