A Blog For Those Affected By Environmental And Invisible Illnesses Written By Fellow Survivors
Environmental factors steps up in autism
Tom Insel, Director of the National Institute of Mental Health (NIMH) is quoted in his recent blog entry titled 'Autism Spring' as saying about autism "The answers — and there will be answers — will no doubt merge genetic risk and environmental exposure to help us reach the far side of the complexity of ASD". Whilst to many this sentence has made sense for many years, it is indeed a 'game-changer' when the Head of the one of National Institutes of Health makes such a bold statement. One might even suggest that his words define a new era in autism research where genetics share the throne with environment rather than environment somehow being seen as the distant cousin.
What might lead Dr Insel to make such bold claims? Could it be that 2011 might just be the year when the worm turns. Indeed, 2011 has witnessed several interesting findings in relation to research into autism spectrum conditions, some of which I will include here.
1. Copy Number Variations (CNVs). Those tiny losses and gains in DNA sequences. This paper really lit the fuse by demonstrating just how complicated autism can be in genetic terms. Lots and lots of CNVs, some overlap between various groups with autism, but by no means a straight forward universal genetic explanation of autism.
2. Mutation. Several studies summarised in this editorial. Many genetic mutations identified in participants with autism were de novo, so not inherited from either parent. Where did they come from?
3. Monozygotic vs. dizygotic twins. This paper published only days ago (at the time of writing this entry) has created significant interest. Their findings, based on the one of the largest participant groups studied in this area, are not that dissimilar from previous studies of twins derived from either one or separate eggs. The modelling of the data however suggests that the significant leaning towards heightened levels of autism in monozygotic twins is perhaps also accompanied by levels of autism in dizygotic twins not previously noted in similar twin studies. In short, inheritance counts for something, but so might environment.
4. SSRI use, vitamin use and birth factors all suggested as risk (or protective) factors for autism. Maternal SSRI use in early pregnancy, whilst rare, might increase the risk of autism in offspring. Early vitamin use either prenatally or perinatally combined with various mutations might affect the risk of autism in offspring. A meta-analysis of the various birth factors previously associated with autism suggests several significant predictors, despite no one pattern of factors being related to autism risk.
Whilst none of these studies provide definitive answers about autism and its possible aetiology (or rather aetiologies, plural), there are some strong messages emerging from the collected data. It is not about disproving a role for genetics in autism. It is more about suggesting that genes do not work in isolation, and our ever-changing environment complete with its modern-day chemical, pharmaceutical and toxicological elements, cannot be ruled out of any relationship with autism spectrum conditions.
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