The power and pitfalls of omics part 2: epigenomics, transcriptomics and ME/CFS
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Surveys on MTHFR mutations among the population?

Discussion in 'Detox: Methylation; B12; Glutathione; Chelation' started by bsw, Sep 6, 2016.

  1. bsw

    bsw w/r/t

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    A month or so ago I confirmed that I have MTHFR mutations. Since then I have been taking L-5-MTHF and my health has begun to improve.
    This got me thinking about the prevalence of these mutations throughout not just CFS suffers, but also the population in general. Just how prevalent is MTHFR among people in society? I have seen some evidence that it correlates with conditions like depression, autism and other mental conditions. I couldn't find any research looking at this sort of thing in the overall population. Can anyone help me out by pointing me in the direction of any research on this sort of thing?
     
  2. alicec

    alicec Senior Member

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    There are a number of SNPs on MTHFR with different frequencies, but I assume you are referring to the two that appear frequently in internet chatter, rs1801133, aka C677T and rs1801131, aka A1298C.

    Both these SNPs are common worldwide with a minor allele frequency (ie the frequency of the changed nucleotide) of roughly 0.25. So about 1/4 of the world's population carries these variants.

    You just need to go to this site, type in the rs number you are interested in and it will bring up information like MAF (minor allele frequency), details of where the change occurs in the gene, whether it affects the amino acid sequence and hence is likely to have some effect, plus links to research.

    Some earlier small association studies did link these variants to some of the conditions you mention. I'm not sure how valid they are. Certainly I recall a recent, very extensive genome-wide association study which was looking at genetic variants associated with depression. Some genes did have a small association but MTHFR was not among them.

    I think you will find many of the other associations disappear when a sufficiently large study is made.
     
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  3. taniaaust1

    taniaaust1

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    I read somewhere that MTHFR mutation (I think they may of been refering to C667T kind) varies from 6 (or maybe it was 7) to 19%. There are different rates in different countries.
     
  4. taniaaust1

    taniaaust1

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    I just found this which is interesting as its so high http://www.ncbi.nlm.nih.gov/pubmed/10494095

    the comparision group for the Ashkenazi Jewish ones was those from South Texas. That study isnt clear to me if they were refering to double copies of the mutation or just single copy.
     
  5. Valentijn

    Valentijn The Diabolic Logic

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    They are extremely common. MTHFR C677T has a Minor Allele Frequency (MAF) of 30%, and MTHFR A1298C has a MAF of 29.5%. This means about 42% ((1-MAF) x MAF x 2) of people will be heterozygous for each one, and 9% (MAF x MAF) will be homozygous for each one. So over half of the general population has each one of these MTHFR SNPs.

    Since these SNPs aren't in strong linkage disequilibrium, it's not always going to the same people having both mutations. So it's probably around 75% of the world's population which is heterozygous or homozygous for one or both mutations. When I took a look at 23andMe data for 31 ME patients and ethnically matched controls, both groups had a reduction of about 40% of gene functionality.

    There's pretty much no chance that these MTHFR mutations are causing disease, aside from folate-related birth defects, especially if the people with these mutations are eating some vegetables or taking a multivitamin.
     
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  6. alicec

    alicec Senior Member

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    I'd better check the source of my approx. 0.25 figure. Maybe it was from a particular population than more general.
     
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  7. Valentijn

    Valentijn The Diabolic Logic

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    dbSNP has been getting in some pretty huge mixed population samples over the past year or so, so some values have been changing quite a bit :p
     
  8. ahmo

    ahmo Senior Member

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    Ben Lynch's mthfr.net is the most comprehensive site I've found. You might find figures there.
     
  9. alicec

    alicec Senior Member

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    Lynch does no genetic research (he is a naturopath who treats patients and sells supplements). If you did find such figures on his website they would be derived from the extensive database maintained by the NIH which is referenced above. As well as the global figures mentioned, you will find figures for allele distribution among many ethnic groups.
     
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  10. alicec

    alicec Senior Member

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    I see what you mean. The newer 30% figure is based on 36,864 genomes. The older 25% figure on 1,229 genomes.
     
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