The MTRR A66G mutation is a defect of the methionine synthase reductase gene. A mutation of the MTRR A66G gene results in poor methylation of vitamin B12. Serum B12 levels may be normal in MTRR A66G (+/+) or (+/-) individuals; however, the under-methylation of vitamin B12 may result in elevated homocysteine levels. If you have high homocysteine, it may be due to the MTRR A66G mutation.
You can easily find out if you have the MTRR A66G mutation by ordering a DNA test kit from 23andMe ($99). Once you receive your results, go to Genetic Genie for methylation analysis (free). If your results show you have the mutation, you should consider supplementing with methylcobalamin and methylfolate.
You can address the MTRR A66G mutation by taking methyl-B12 supplements, usually in doses of 1,000-2,000 mcg per day. If you have both an MTRR A66G mutation and an MTR A2756G mutation, you may want to consider higher doses, up to 5,000 mcg per day.There are many options to consider, but it is important to distinguish between methylated forms of B12 versus the more common B12 supplements. Most B12 supplements contain cyanocobalamin, which does not benefit someone with the MTRR A66G mutation. Make sure the form of B12 you take contains methylcobalamin. Here are two good options:
Jarrow Formulas Methyl B-12, 1,000 mcg
Jarrow Formulas Methyl B-12, 5,000 mcg
Because vitamin B12 and folate work synergistically in the body, you want to make sure the two vitamins are in balance. Therefore, if you are supplementing one, it is usually a good idea to supplement the other. It is especially important to supplement with methylfolate if you also have the MTHFR C677T or MTHFR A1298C mutation. As with B12, you will again want to choose a methylated form of folate to ensure it is utilized in its active form. Here are some good choices:
Solgar Folate (as Metfolin), 800 mcg
Thorne Research 5-MTHF (as Extrafolate-S), 1 mg
Thorne Research 5-MTHF(as Extrafolate-S), 5 mg
The MTRR A66G mutation indicates the need for the active form of vitamin B12—methylcobalamin. You should also consider supplementing with methylfolate, in order to ensure these two vitamins are in balance.
Disclaimer: The information on this site is not intended to be used in place of professional medical advice or treatment, nor is it intended to diagnose, treat, or prevent any disease. Always seek the advice of your physician or other qualified healthcare provider before taking any supplements.