I have high 5-MTHF levels in the cell. Theoretically this would mean that MTHFR and/or MS and/or MTRR don't function. My SNP's support these possibilities, see below. But I was already supplementing with iron and B12 when the test was taken (B12 levels >1000, ref. 350-750). My wife also has this and has CFS. We both have HHV-5. This is from my Yasko Panel: +/+ MAO A; BHMT 8 +/- MTRR H595Y, K350A, 11; COMT V158M, H62H; VDR Fok; ACE Del16; MTHFR C677T, A1298C; BHMT 2, 4; AHCY 1, 2, 19; CBS A360A; SHMT C1420T Any other suggestions about how to lower 5-MTHF and what's wrong? I feel that I can't take more B12, because that causes low back pain which I think means I 'm dosing too high. And my B12 blood levels are already high enough.