Very interesting discussion with lots of useful links - thanks everyone.

Just to throw in my 2 cents worth - I've been looking recently for scientific research on possible links between MTHFR gene mutations and prevalence of autoimmune disease, (specifically Fibromyalgia and/or Addison's Disease). This may have some relevance to the discussion of genetic influence and disregulation of the immune system. I know MTHFR has been discussed on other threads here on NT, so the link below may already be known.

Association study between methylenetetrahydrofolate reductase gene polymorphisms and Graves' disease. - PubMed - NCBI

While it's only an abstract, and it specifically discusses Graves Disease, it does say: "Previous studies have provided evidence that a high prevalence of MTHFR gene polymorphisms is frequently detected in patients with autoimmune disease, suggesting a novel genetic association with autoimmune disorders." (Interestingly this study's conclusion is that in the case of Graves Disease - MTHFR actually provides a protective effect in women.)

I've only just started looking so will post any further sites I come across later. There's plenty of anecdotal supposition online, (of the flog the book, treatment or supplement type), but finding definitive information is more elusive.

Would appreciate if anyone else who comes across anything connected could post a link. Thanks