Meta-analysing MTHFR and autism

I told you so.

I'm talking about the paper by Pu and colleagues* who meta-analysed the currently available literature looking at two SNPs in everyone's favourite Scrabble classic gene, MTHFR in relation to autism spectrum disorders (ASDs). Said gene controls production of methylenetetrahydrofolate reductase (MTHFR) which fits very snugly into the whole one carbon metabolism cycle (see here).

Love at first sight? @ Wikipedia  

Regular readers might know that I have a bit of a thing for MTHFR with autism in mind. And how MTHFR serves an important purpose in reducing the compound 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate and onward its links to homocysteine (see here) and methionine (see here) and all that methylation palava.

For a good summary (well, at least I think so) you might also want to have a look at this older post detailing the process, complete with hand-drawn diagram by yours truly.

In essence, Pu et al reiterated the important role than the MTHFR C677T SNP might have to some cases of autism; in particular how "the C677T polymorphism was found to be associated with ASD only in children from countries without [folic acid] food fortification" denoting the potentially important link with the vitamin of the hour, folate (folic acid, vitamin B9) (see here).

There's little more for me to add to this post that hasn't already been said. MTHFR is probably not going to be an issue for everyone with autism, and indeed might also be potentially important to other conditions outside of the autism spectrum (see here for a discussion of that recent schizophrenia paper). Mmm... perhaps another part of that common ground and potential RDoC variable?

The nutrition link is perhaps something which adds to the view that environment might be a modifier of risk of some ASDs bearing also in mind the overlap with things like vitamin B12 (see here). That being said I'm also going to draw your attention back to all that folate receptor autoantibody stuff too just to bear in mind.

I told you so.

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* Pu D. et al. Association between MTHFR gene polymorphisms and the risk of autism spectrum disorders: a meta-analysis. Autism Res. May 2013.

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Pu D, Shen Y, & Wu J (2013). Association between MTHFR Gene Polymorphisms and the Risk of Autism Spectrum Disorders: A Meta-Analysis. Autism research : official journal of the International Society for Autism Research PMID: 23653228