Yes, there have been threads on this website about this. The more frequent culprit is B12. I think the problem is with the methylization process, so with B12 the supplement needed is methyl B12. But the genetic deficiency can also be folate or B6. The three are in balance with one another and are often implicated in the same things. The difficulty is, while the genetic defect is found in lots of people, it isn't thought to have an effect on very many of them and that can be a problem because supplementing with methylated Bs can be a problem if that's not your issue. If you search the site you'll find some lengthy discussion about this that were quite interesting, but I can't remember who raised the issue and which forum it was on.