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Secondary structure (structure of proteins that show alpha-helices and beta-sheets) of MTHFR.
The "spirals" symbolize alpha-helices (α-helices) while the "arrows" stand for beta-sheets (β-sheets).
The numbers on these elements denote the amino acid position (i.e. where on the total sequence a particular structure begins and ends).
N and C denote, respectively, the beginning (amide group: -CONH2) and the end (carboxyl group: -CO2H) of the protein.
Live, reproduce, die
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Great Apes

Methylenetetrahydrofolate reductase (MTHFR), is an enzyme[1] related to the methyl cycle involved in B vitamins. Many people have variations (usually harmless) in the MTHFR gene.

Role in health conditions[edit]

Mutations in the MTHFR gene have been proposed to be linked to everything from autism to nerve pain to leukemia.[2] Some early studies suggested that people with certain diseases had MTHFR variants, only for researchers to discover that the variants were just as common in healthy people.[3] Many of these proposals nowadays come from naturopaths and quacks, based completely on anecdotal evidence.[4]

In most cases, however, people with MTHFR variants just need a little extra vitamin B.[5] Their levels of homocysteiene may be average or above average. An above-average level may put them at higher risk for a few health conditions.[6]

Unclear associations[edit]

Research is not yet clear on whether people with MTHFR variants are at higher risk of heart disease, blood clots, cancer, and other conditions.[7]

Neural tube defects[edit]

Children of people with two C677T variants are at 0.14% risk that they will have a neural tube defect. A folate supplement will reduce this risk.[8] If neural tube defects run in the family, prospective parents can consult a doctor about an appropriate supplement.


Homocystinuria is a rare condition related to impaired metabolism of folate (vitamin B9) due to MTHFR enzyme deficiency. It is present from birth and can be treated with supplements. Symptoms include (from most to least common):[9]

  • Developmental delay and intellectual disability
  • Low muscle tone
  • Seizures
  • Failure to thrive
  • Abnormal blood clotting
  • Microcephaly (small head)
  • Ataxia (poor coordination)
  • Peripheral neuropathy (numbness, tingling, or pain in the hands and feet)


See the main article on this topic: Pseudoscience

Scam artists encourage people to test for MTHFR variants and send their genetic information to the scammer. Then, the scammer can find things that are "wrong" with the person and sell them supplements, restrictive diets, and other "solutions". However, experts consider MTHFR testing to be unnecessary, except in unique cases,[10] and some have gone so far to recommend against it so that patients do not waste their time.[11][12]

The supplements they sell may not be safe, either. Taking too much folic acid may increase the risk and severity of cancer.[13]

MTHFR and vaccines[edit]

Despite rumors, children with MTHFR variations can be vaccinated normally.[14]

Fake autism cures[edit]

Researchers are still cautious about whether there is a meaningful link between polymorphism in the MTHFR gene and autism.[15][16] Yet charlatans have charged on ahead to sell fake autism cures claiming to be related to MTHFR. These "cures" can cost thousands of dollars, and they give families false hope of changing their children (instead of just accepting that their kid is autistic).[17]

See also[edit]