Tuesday, 19 April 2011

MTHFR and autism

If I say the letters 'MTHFR' would you know what I was talking about?

Up until about 4 or 5 years ago, I would have said something along the lines of 'some great consonants to play scrabble with'. But no, MTHFR in this case stands for methylentetrahydrofolate reductase. A bit of background first. MTHFR is an enzyme produced by the MTHFR gene which reduces (hence the name) the compound 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. That might not sound like much, but importantly this is a pretty vital step in one of the routes converting the amino-acid homocysteine to methionine.

Readers may already know that I have blogged about 'the big H' homocysteine (and homocystine) in relation to autism previously. Homocysteine is acquiring quite a following with regards to several things including risk of coronary heart disease (perhaps even greater a risk than cholesterol?).

Assume then that you have a problem with the MTHFR enzyme or gene which means that it does not quite perform the functions it is supposed to do. You could quite easily see how that conversion of homocysteine to methionine might not be as efficient as it should be and potentially lead to a build-up of homocysteine in plasma (and urine - homocystinuria). Not trying to scare anyone, just show how important MTHFR is.

MTHFR has also been of some interest in relation to autism spectrum conditions. There was this paper a few years back looking at a particular SNP (pronounced 'snip') of the MTHFR gene in relation to the methionine cycle and folate metabolism. The same SNP of the MTHFR gene has also been looked at in this paper and this paper. The suggestion being that problems with MTHFR isolated in these studies might indicate issues such as impaired methylation of DNA (a kind of switch which turns certain genes on or off) which linked to autism has been postulated in papers such as this one as being important.

There is still a lot more work needed on the central role of MTHFR in relation to autism and homocysteine, folate metabolism and DNA methylation.  Perhaps next time you get the letters M-T-H-F-R as your scrabble word collection or see them on Countdown, spare a thought for the importance of methylenetetrahydrofolate reductase in our lives.