A familial element to homocysteine elevations in schizophrenia?

Homocysteine - the big H - really should have its own Twitter hashtag... #thebigH.

Not only because of the range of health-related conditions which seem to be correlated with particular levels of this amino acid - think coronary heart disease and elevated homocysteine for example* or more recently cerebrovascular disease** - but also because of the body of work linking elevated homocysteine levels to diagnoses like autism and schizophrenia. (Yes, I know correlation does not equal causation).

The Benzon daughters @ Wikpedia 

In this post, I'm laying off the fairly numerous studies looking at homocysteine in relation to autism (see here and here for example) and how it potentially fits into all that folate and methionine cycle stuff.

Instead I'm concentrating on the paper by Geller and colleagues*** reporting on an interesting observation of elevated homocysteine levels in male siblings of people diagnosed with schizophrenia.

I was drawn to post about this paper for several reasons: (a) continuing the link between the big H and schizophrenia (see here), (b) the suggestion that the big H link might also have a familial element and (c) ergo, the possibility of a kind of shared biological phenotype being present in at least some families of those diagnosed with schizophrenia. This last point in particular might not necessarily just mean elevated risk of schizophrenia - if one is to assume that elevated levels of homocysteine is a factor - but also all those other health-related links being made with homocysteine.

The familial element also brought me back to autism and concepts like the broader autism phenotype (BAP) and indeed, some of the shared biochemistry that seems to be present in some cases of autism (see here). On that basis, I guess it should be no surprise about what Geller et al found if one is to assume some similar scenario also pertaining across schizophrenia or the schizophrenia spectrum.

There's little more for me to say about the Geller findings aside from replication please and perhaps detailing a little more about those siblings (i.e. did they go on to develop schizophrenia or any other related condition?) In passing I mentioned about the folate and methionine link which brings in those letter MTHFR; by all accounts, this seems to be quite an important part of that homocysteine link****. Oh and then there's the body of research which seems to imply we might be able to do something about hyper-homocysteine***** and related parameters (see here). Bearing in mind that I give no medical or clinical advice about this...

Music: Don't Stop Believin' by Journey. Please, proper English gentlemen... believing.

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* Humphrey LL. et al. Homocysteine level and coronary heart disease incidence: a systematic review and meta-analysis. Mayo Clin Proc. 2008 Nov;83(11):1203-12.

** Yan J. et al. Vitamin B supplementation, homocysteine levels, and the risk of cerebrovascular disease. Neurology. 2013; 81: 1298-1307.

*** Geller V. et al. Elevated homocysteine level in siblings of patients with schizophrenia. Psychiatry Res. 2013 Sep 16. pii: S0165-1781(13)00476-9. doi: 10.1016/j.psychres.2013.08.016.

**** Muntjewerff JW. et al. Homocysteine, methylenetetrahydrofolate reductase and risk of schizophrenia: a meta-analysis. Mol Psychiatry. 2006 Feb;11(2):143-9.

***** Miodownik C. et al. High-dose vitamin B6 decreases homocysteine serum levels in patients with schizophrenia and schizoaffective disorders: a preliminary study. Clin Neuropharmacol. 2007 Jan-Feb;30(1):13-7.

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Geller V, Friger M, Sela BA, & Levine J (2013). Elevated homocysteine level in siblings of patients with schizophrenia. Psychiatry research PMID: 24051177