I recently received my 23andMe results and analyzed them for methylation SNPs. I'm heterozygous (AG) on a few, including MTHFR C677T and MTRR A664A, and homozygous (GG) on MTRR A66G. I'm trying to figure out what the MTRR mutations mean, in particular, as far as what is going on in my body. I know my MTRR A66G is bad news, but how much, if at all, should I worry about my MTRR A664A? I've looked for more detailed info but have been unable to find it. Also, as I understand it (and please forgive my simplified explanation), MTRR is involved in recycling used methylcobalamin back into a useable state. The solution is to take large doses of methylcobalamin to compensate. But with this mutation, doesn't that also mean that my body is accumulating a larger than normal amount of used methylcobalamin? What happens to it, and can it cause any additional problems?