Familial autoimmune disease and offspring autism risk

"An overall increased risk of autism in children with family history of ADs [autoimmune diseases] was identified."

That was the bottom line of the "systematic review and meta-analysis" carried out by Shunquan Wu and colleagues [1] summarising the "current evidence on the relationship between family history of autoimmune diseases (ADs) and risk of autism in children." Autoimmune disorders by the way, are the various conditions that come about when the body fails to recognise self as 'self' and the immune system mounts an offensive against healthy tissue as if they were 'other' by mistake.

Regular readers of this blog might already know that I'm an avid follower of the idea that autoimmunity might show more than a passing connection to at least some cases of autism (see here) among other things (see here). Bearing in mind that autoimmunity might be just one immune system 'presentation' linked either directly or peripherally to autism (see here) I've read enough peer-reviewed evidence on the topic to be convinced that quite a bit more resource and research power should be dedicated to seeing just how deep the rabbit hole gets [2].

The Wu paper lists a number of specific ADs as showing something of an important 'correlation' to offspring autism risk including:

• "a statistically significant association with family history of hypothyroidism." Hypothyroidism - an underactive thyroid gland - is quite commonly due to the presence of autoimmune thyroiditis (a condition that has been mentioned once or twice on this blog). Hypothyroidism, maternal hypothyroidism, is potentially something important to offspring autism risk as per other research discussions (see here).
• A familial history of type 1 diabetes - where the pancreas doesn't produce insulin - is also mentioned as a risk factor. In amongst the research looking at the various types of diabetes and how they may have an important bearing on autism (see here), type 1 diabetes has previously cropped up on more than one occasion (see here).
• Psoriasis - a blanket term for various autoimmune mediated skin conditions - is also identified by Wu et al as a possible risk factor for offspring autism. Again, I've talked about this condition in relation to autism before on this blog (see here).

"More mechanistic studies are needed to further explain the association between family history of ADs and increased risk of autism in children." I'd very much agree with the parting sentiments discussed by the authors on this topic. Appreciating that genetics (see here) and environment (see here) seemingly combine when it comes to the appearance of autoimmune disease, such studies of potential mechanism might need to be rather broad in their remit. I'd also put forward the notion that some potentially important data may also be garnered by looking at other facets of our genes outside of just the HLA (human leukocyte antigen) region [3] as per the growing body of work talking at HERVs (human endogenous retroviruses) and autoimmunity potentially intersecting with the science of epigenetics [4]. Oh, and in case you'd like a little more background on HERVs, a small contribution from me on the subject (see here)...

Music: Ben E. King - Stand by me.

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[1] Wu S. et al. Family history of autoimmune diseases is associated with an increased risk of autism in children: a systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews. 2015. May 15.

[2] Gesundheit B. et al. Immunological and autoimmune considerations of Autism Spectrum Disorders. J Autoimmun. 2013 Aug;44:1-7. 

[3] Gough SC. & Simmonds MJ. The HLA Region and Autoimmune Disease: Associations and Mechanisms of Action. Curr Genomics. 2007 Nov;8(7):453-65.

[4] Lavie L. et al. CpG methylation directly regulates transcriptional activity of the human endogenous retrovirus family HERV-K(HML-2). J Virol. 2005 Jan;79(2):876-83.

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Wu, S., Ding, Y., Wu, F., Li, R., Xie, G., Hou, J., & Mao, P. (2015). Family history of autoimmune diseases is associated with an increased risk of autism in children: a systematic review and meta-analysis Neuroscience & Biobehavioral Reviews DOI: 10.1016/j.neubiorev.2015.05.004