Methylation & Homocysteine Pathways

The folate cycle and homocysteine

Methylation means adding a small chemical tag (a methyl group) to other molecules. It's involved in making and repairing DNA, processing the amino acid homocysteine, and producing and breaking down some neurotransmitters.

Folate from food has to be converted into its active form, 5-methyltetrahydrofolate, before the body can use it. The enzyme that performs one of the key steps is made from the MTHFR gene. Vitamin B12 is then needed to use that active folate to turn homocysteine into methionine. When this cycle runs slowly, homocysteine can build up in the blood.

MTHFR

Two common MTHFR variants, often called C677T and A1298C, can reduce the enzyme's activity. They are very common.

• People with two copies of C677T tend to have somewhat higher homocysteine levels, mainly when their folate intake is low.
• On their own, these variants have not been shown to cause a specific illness, and several medical organizations don't recommend routine MTHFR testing.

COMT

The COMT gene makes an enzyme that uses a methyl group to break down catecholamines, such as dopamine, adrenaline and noradrenaline, as well as some estrogens. A common COMT variant affects how quickly the enzyme works. Research has linked it to differences in stress response and other traits, but findings are mixed and it doesn't diagnose any condition.

Which tests cover these genes

• Genetrack DNA Thrombotic Risk Test reports MTHFR variants, along with F5 (Factor V Leiden) and F2 (prothrombin) clotting variants.
• dnaPower totalPower includes methylation genes such as MTHFR and COMT, as described by dnaPower.
• Genetrack DNA Nutrition Test reports genetic tendencies for folate (B9) and B12, both central to the cycle.

"DNA methylation" or epigenetic tests are different. They measure methylation marks on DNA itself. See Epigenetics & Biological Aging.