The MTHFR C677T and MTRRK350A +/+ would both slow the respective enzymes, especially the former.
Both these enzymatic reactions are required to be functional for methionine synthase (MTR) to work well, so it is a bit of a double whammy.
Having said that, these variants a fairly common, so they are not going to be the cause of your health problems, though could certainly be making a contribution.
For MTHFR, supplementation with its cofactor B2 may help stimulate a sluggish enzyme, and supplementation with the end product of the reaction, methylfolate, may also be helpful.
A slow MTRR may mean the B12 is not recycled well, ie it is in a sense wasted. Supplementation with methylB12 may be helpful.
Here is a post I wrote recently about more general issues involved with active B12 supplementation.
The only other SNP which has any consequence is the first COMT. +/- would have a slight slowing of the enzyme. Supplementation with the cofactor magnesium might be helpful.
It is claimed the COMT SNPs mean intolerance of methyl groups. This is a theory with no evidence, and plenty of people who are COMT +/+ have no trouble with methyl groups.
Some are very sensitive to supplements like methylfolate and methylB12, so proceed cautiously, but it has nothing to do with COMT.
