MTRR A664A: I have read everything I can find about this mutation and I am still kind of confused on how to approach it. I'm obviously not approaching it correctly as I still feel terrible. I understand that I need increased methylcobalamin with this mutation, but how much? I also read I may or may not to be supplementing hydroxycobalamin; if so, how much per day? And this mutation prevents me from converting homocysteine to methinonine, so should I supplement l-methionine? I also read that supplementing l-methionine increases homocysteine levels...and that is not good. I also have the VDR Taq and MAO-A R297R homozygous mutations. I know I need Vitamin D for VDR Taq but I can't find anywhere that talks about dosages. I am currently taking 10,000 iu per day. Should I try 25,000 IU or more? And for the MAO-A R297R, I guess I need to be supplementing 5-htp or St. John's wort but also read that this mutation INCREASES neurotransmitters because the body can't break it down fast enough. How does it make sense to add additional 5-htp if the body isn't already breaking down my neurotransmitters fast enough? Please, anyone who has experience with these homozygous mutations, I could really use your help! Thanks.