@mitchgord, you are absolutely correct! My daughter is a homozygous c677t sufferer and so is my grandson. There is a lot that is not understood about the MTHFR gene mutations and there is a lot of incorrect information out there. The advice seems to be that it is not necessary to test for the MTHFR gene at all as the treatment plan would be the same... and then the advice is to test for homocysteine in blood and to fill up on B vitamins if the homocysteine is high. The problem with this is that the people giving this advice do not seem to fully understand the job of MTHFR and how methylation actually works. If you for example have two defective copies of the C677T mutation (which you will only know if you do in fact do the gene test), then your body struggles with methylation, meaning it cannot properly use the B vitamins. Taking the synthetic folic acid, that is not only in supplements, but also widely added to fortified foods like bread flour and breakfast cereals, cannot be used by the already broken methylation system of the homozygous c677t sufferer and as you say, it makes things even worse as it interferes with the little bit of folate your body may still be able to metabolize... But this folic acid will be picked up in blood tests before being discarded by the kidneys, so the patient looks like they are not B9 deficient at all, while in actual fact, they are. B12 is another such vitamin. B6 is even worse, because even though it is water soluble and should be leaving the body via the kidneys, it actually takes a long time to do so and therefore tends to build up in the blood... to toxic levels which causes all sorts of nasty, nasty symptoms. There are actually B vitamins that can be prescribed, that are easier for MTHFR sufferers to absorb and metabolize, but they are not the ones being prescribed! Also, these synthetic B vitamins can potentially mask what is going on with the homocysteine levels, leading to misdiagnosis. And if the methylation system of the body is broken, it leads to all sorts of issues, issues that are prevalent in modern life, not well understood and for which so many patients are being gaslit, told the pain and fatigue is imagined, in their heads etc. A very recent study at Tulane University in Florida has shown that there is a strong link between the MTHFR gene and hypermobile Ehlers-Danlos Syndrome (hEDS). It would explain so many of the symptoms of EDS patience, the pain, the chronic fatigue, collagen issues, bone issues, IBS etc, etc, etc. Another recent study has found that ME patients, though they had normal blood homocysteine levels, all had elevated homocysteine in their spinal fluid! I believe that there is a huge under reporting of the MTHFR gene polymorphism and GPs have no idea of what to look for and what the results mean. I think if this part of medicine was better understood, we would find answers to many of our unexplained modern-day illnesses. Living with chronic pain and fatigue and all the other symptoms, is soul destroying….