There are a number of webpages devoted to these mutations, however the short and sweet of it is that (at least for my situation) my body is running at 60% normal activity in regards to enzyme activity. This enzyme is involved in the metabolism of folate and homocysteine.
Basically is means that your body isn't working the way it should, and to help it you need to do a couple of things. Specifically you need to supplement with the right folate and B-vitamins.
Most B-complex, multi-vits, and individual B vitamin supplements will end up being the wrong kind for you, if you have these mutations. What are the right kind? The kind with the word "methyl" in front of them. For the multi-vitamin I take, which I mentioned in the previous post, it has both methylcobalamin (the right kind of B12) and L-5-methyltetrahydrofolate (the right kind of folate).
It also has the right kind of B12 and folate. Both of these brands of vitamins were recommended to me by my naturopath.