B6 Toxicity is such a relatively new ailment that there is not enough known about it to say for sure. From what I've read on the B6 Toxicity board on medhelp, many doctors discount their patients' symptoms and tell them "you can't have B6 Toxicity, it doesn't exist, the B6 Vitamin is water soluble" or they tell them "if you had B6 Toxicity, it would have resolved itself by now, you can't still be suffering." But anecdotal evidence seems to indicate that it is possible to suffer from neurological problems that only seem to have been caused by an overdose of *man-made* Vitamin B6. And a lot of the people who have these symptoms and have had them for several years are then getting tested for MTHFR and are finding that they do have MTHFR. So, these patients are starting to deduce that the two are related. That's all I know.
I for sure have MTHFR. I have neurological problems that began in 2007 when I started taking 150mg-200mg of B6/day. I'm not sure if I have B6 Toxicity as I've seen 22 doctors now and no one has given me an official diagnosis. But my guess is that because my body has a hard time digesting and metabolizing chemicals, I either have nerve damage from the B6, or some type of toxin in my body that I can't get rid of which is causing me neuropathy.
Hi Bev I also have Pyridoxine toxicity AND I have the MTHFR gene mutation. I also have the auto-immune disease hashimoto's thyroiditis (hypothyroidism). I believe they are all related. MTHFR controls methylation of B6, 12 and folate. Most people think that means insufficiency, but actually in the case of B6 means toxicity. I have neuropathy in my feet and muscle weakness as a result. I am not taking any B6 supplementation.