Saturday, 25 October 2014

Autism and intolerance of uncertainty

Good morning, gentlemen,
the temperature is 110 degrees
'Change' is often mentioned as something potentially problematic for many on the autism spectrum, and how unexpected change can sometimes have profound effects in terms of those so-called 'challenging behaviours' or when it comes to the presentation of important comorbidity such as anxiety. Like many others from the outside looking in, I was always taught that change as a more general concept was the important issue in autism, but recently the word 'uncertainty' has been creeping into various discussions that I've seen and in particular, the concept of an 'intolerance of uncertainty' noted in cases of autism.

As far as I can ascertain, intolerance of uncertainty with autism in mind was first described in the peer-reviewed literature by Christina Boulter and colleagues [1] and subsequently by Sarah Wigham and colleagues [2]; both papers originating from the University of Newcastle, here in the bracing North East of England. The Boulter paper initially looked at how intolerance of uncertainty (IU) tied into the expression of anxiety in paediatric autism noting results "consistent with a causal model". The Wigham paper extended these findings, drawing on how the IU-anxiety relationship may also stretch to the presentation (interplay) of sensory issues among other things.

Focusing specifically on the Boulter paper, a few details might be in order (unfortunately the paper is not open-access)

  • IU - defined as "a broad dispositional risk factor for the development and maintenance of clinically significant anxiety" - was assessed as part of a larger research platform looking at anxiety and autism.
  • Derived from various sources (including the Daslne initiative), participants (N=224) including children/young adults diagnosed with an autism spectrum disorder (ASD) (n=114) and asymptomatic controls (n=110) were assessed for IU via the Intolerance of Uncertainty Scales (child and parent report versions). "The scale assesses IU by asking respondents to rate the extent to which statements relating to emotional, cognitive and behavioural responses to uncertainty are like them, or... like their child". Various other measures including the SRS and the Spence Children's Anxiety Scales (SCAS) were also delivered to participants.
  • Results: well as if we needed telling "children with ASD showed higher levels of anxiety than TD [typically developing] children". As per previous discussion on quality of life and autism, the question of who reports anxiety (first person vs. second person reports) featured in the Boulter findings, although "disagreement appears to have been more pronounced in the TD group than in the ASD group". 
  • Children with ASD were also reported to have "significantly higher levels of IU" and such elevations in IU "accounted for the increased levels of anxiety in the children with autism" hence the previous chatter about causal models et al. Perhaps also importantly, the relationship between IU and anxiety "was the same in both children with ASD and those without" so "similar processes may be at work within both populations".

There are some obvious caveats to these results. The authors point out that their focus on ability "within the normal range" as a function of their questioning is a limitation, and the 'caution' that goes with "generalising conclusions to all children with ASD". I might add that the introduction of a non-ASD anxiety-only control group would probably not have gone amiss either. Drawing on the more general literature on IU, the findings from Yook and colleagues [3] might also suggest that additional measures of worry and rumination (another important concept [4]) might have been useful to investigate too. This may be particularly important given the reports of overlap in depressive-type symptoms/syndromes occurring alongside cases of autism. Me being me, I would also have liked to seen some physiological measure(s) included too...

Still, I am rather intrigued by these initial findings on IU and how they may potentially fit into the often very disabling anxiety which can accompany a diagnosis of autism. If anything else, they may present a further target for intervention - bearing in mind the need for further research on the use of something like CBT for anxiety in autism - with the aim of improving quality of life.

Music to close, and continuing a recent theme on this blog: The Smiths and Ask (yes, I have been listening to their greatest hits, and yes, they probably were one of the best bands ever).


[1] Boulter C. et al. Intolerance of uncertainty as a framework for understanding anxiety in children and adolescents with autism spectrum disorders. J Autism Dev Disord. 2014 Jun;44(6):1391-402.

[2] Wigham S. et al. The Interplay Between Sensory Processing Abnormalities, Intolerance of Uncertainty, Anxiety and Restricted and Repetitive Behaviours in Autism Spectrum Disorder. J Autism Dev Disord. 2014 Sep 27.

[3] Yook K. et al. Intolerance of uncertainty, worry, and rumination in major depressive disorder and generalized anxiety disorder. J Anxiety Disord. 2010 Aug;24(6):623-8.

[4] Hare DJ. et al. Anxiety in Asperger's syndrome: Assessment in real time. Autism. 2014 May 8.

---------- Boulter C, Freeston M, South M, & Rodgers J (2014). Intolerance of uncertainty as a framework for understanding anxiety in children and adolescents with autism spectrum disorders. Journal of autism and developmental disorders, 44 (6), 1391-402 PMID: 24272526

Friday, 24 October 2014

Autism, siblings and DSM-5 Social Communication Disorder

A quick post to bring to your attention the paper by Meghan Miller and colleagues [1] who concluded that: "Pragmatic language problems are present in some siblings of children with ASD [autism spectrum disorder] as early as 36 months of age". Further: "As the new DSM-5 diagnosis of Social (Pragmatic) Communication Disorder (SCD) is thought to occur more frequently in family members of individuals with ASD, it is possible that some of these siblings will meet criteria for SCD as they get older".
Isn't this a school day?

The DSM-5, as many in the autism community will already know, has been the source of quite a bit of discussion/argument as to how it has started to re-define what we label as autism or autism spectrum disorder. The initial signs have been that use of the DSM-5 criteria does indeed impact on the numbers of cases of autism (see here) and in particular, that the category termed 'Social Communication Disorder' (SCD) is filling up with those who might present with social communication issues without the repetitive or restricted behaviours required to fulfil the ASD label. Whether this implies the same levels of services and resources will be available to those with SCD as it is supposed to for those with ASD remains to be seen.

I did wonder whether the Miller findings were an important indication (although not the first [2]) that science might also be putting a bit more flesh on to the bones of the concept of a broader autism phenotype (BAP). Describing the subtle speech and language and social interactive issues described on the diagnostic borderlands of autism [3], it strikes me that there is more than a smidgen of overlap between SCD and the BAP (at least with more strength of data than the suggestion of a link between the BAP and postnatal depression). With cautions down the years about assuming "all children with pragmatic difficulties have autism" [4], does the advent of the SCD diagnostic category offer a viable alternative?

Music to close, and the sheer brilliance of Morrissey (live). And for those who might want to know a little more about the man behind the music: The Importance Of Being Morrissey.


[1] Miller M. et al. Early pragmatic language difficulties in siblings of children with autism: implications for DSM-5 social communication disorder? J Child Psychol Psychiatry. 2014 Oct 15.

[2] Botting N. & Conti-Ramsden G. Pragmatic Language Impairment without Autism. Autism. 1999; 3: 371-396

[3] Dawson G. et al. Defining the broader phenotype of autism: genetic, brain, and behavioral perspectives. Dev Psychopathol. 2002 Summer;14(3):581-611.

[4] Bishop DV. & Norbury C. Exploring the borderlands of autistic disorder and specific language impairment: a study using standardised diagnostic instruments.  Journal of Child Psychology and Psychiatry. 2002; 43: 917–929. doi: 10.1111/1469-7610.00114

---------- Miller M, Young GS, Hutman T, Johnson S, Schwichtenberg AJ, & Ozonoff S (2014). Early pragmatic language difficulties in siblings of children with autism: implications for DSM-5 social communication disorder? Journal of child psychology and psychiatry, and allied disciplines PMID: 25315782

Thursday, 23 October 2014

Postpartum depression and the broader autism phenotype?

"The findings suggest that pregnant women with BAP [broader autism phenotype] have an elevated risk for PPD [postpartum depression]".

That was the conclusion reached by Ryosuke Asano and colleagues [1] based on their analysis of data derived from the Hamamatsu Birth Cohort (HBC) Study [2]. The idea being that the more subtle presentation of issues linked to a diagnosis of autism spectrum disorder (the BAP) might predispose to a great likelihood of other behavioural or psychiatric symptoms [3] to be present. We'll see about that.
What're you lookin' at, ya hockey puck?

The Asano paper is open-access but just in case...

  • As part of the HBC study looking at pregnant women to ascertain "an early diagnostic algorithm for [offspring] ASD" [2] researchers garnered various snippets of information from over 800 pregnant women in mainland Japan.
  • Covering mid-pregnancy to approximately 3 months after childbirth, women were asked to complete the Edinburgh Postnatal Depression Scale (EPDS) (a tool fairly routinely used here in the UK) to "measure their depressive symptoms after childbirth". The EPDS was completed 3 times after childbirth (between 2-4 weeks, 5-7 weeks and 8-12 weeks).
  • The BAP was assessed using the Broader Phenotype Autism Symptoms Scale (BPASS) [4] and administered via interview "mainly during the 2nd trimester of the pregnancy". Authors also did some additional work to "check whether our use of the BPASS is reliable and valid". Potential confounders such as a history of depression or anxiety and the level of emotional support provided by partners during pregnancy were also examined in participants; indeed, some 11% of the research cohort "had a history of depression and/or anxiety disorders".
  • Results: "The overall cumulative incidence of PPD was 15.2%". This figure is not a million miles away from other estimates of PPD [4] based on the use of the EPDS (albeit with a slightly different cut-off point). Indeed, the HBC study had already hinted at something around this figure previously [5].
  • Scores on the BAP were "weakly but positively associated with depressive symptoms after childbirth at all measurement periods". I have to say that despite these various correlations being significant, I was not particularly impressed with the correlation (r) values reported (ranging from 0.14 to 0.16 assuming 0 is no correlation and 1 is a perfect correlation). Indeed, when looking at the mean (average) composite score of the BPASS (see Table 1) between the PPD and non-PPD groups you can see there is very little difference in measured BAP (13.77 vs. 13.14).
  • Again, based on the data provided in Table 1, of more interest is the effect of a history of depression/anxiety on PPD status, where 30/128 (23%) and 65/713 (9%) of the PPD and non-PPD groups respectively reported. The authors note that a: "history of depression and/or anxiety disorders was associated with a more than 3-fold increase in the risk of PPD".

With all due respect to the authors, I have to say that I'm not convinced that scoring high on the BAP is truly a major risk factor for postpartum depression. I'm not totally ruling out any relationship as per the Ingersoll findings on the BAP and depressed mood [3] or based on the increasing body of work looking at autism and subsequent mood disorders (see here for example). It's just that there are far more likely predictors/predisposers to PPD than subclinical autistic traits. Indeed, yet another paper from the HBC study [6] further hinted at some of those other factors based on that history of depression/anxiety among other things.

Music then... You've got the love (Florence + The Machine version).


[1] Asano R. et al. Broader autism phenotype as a risk factor for postpartum depression: Hamamatsu Birth Cohort (HBC) Study. Research in Autism Spectrum Disorders. 2014; 8: 1672–1678.

[2] Tsuchiya KJ. et al. Searching for very early precursors of autism spectrum disorders: the Hamamatsu Birth Cohort for Mothers and Children (HBC). Journal of Developmental Origins of Health and Disease. 2010; 1: 158-173.

[3] Ingersoll B. et al. Increased rates of depressed mood in mothers of children with ASD associated with the presence of the broader autism phenotype. Autism Res. 2011 Apr;4(2):143-8.

[4] Verreault N. et al. Rates and risk factors associated with depressive symptoms during pregnancy and with postpartum onset. J Psychosom Obstet Gynaecol. 2014 Sep;35(3):84-91.

[5] Matsumoto K. et al. Age-specific 3-month cumulative incidence of postpartum depression: the Hamamatsu Birth Cohort (HBC) Study. J Affect Disord. 2011 Oct;133(3):607-10.

[6] Mori T. et al. Psychosocial risk factors for postpartum depression and their relation to timing of onset: the Hamamatsu Birth Cohort (HBC) Study. J Affect Disord. 2011 Dec;135(1-3):341-6.

---------- Asano, R., Tsuchiya, K., Takei, N., Harada, T., Kugizaki, Y., Nakahara, R., Nakayasu, C., Okumura, A., Suzuki, Y., Takagai, S., & Mori, N. (2014). Broader autism phenotype as a risk factor for postpartum depression: Hamamatsu Birth Cohort (HBC) Study Research in Autism Spectrum Disorders, 8 (12), 1672-1678 DOI: 10.1016/j.rasd.2014.08.010

Wednesday, 22 October 2014

Autism, parental concerns and socioeconomic status

I'd like to think that there are some rather important messages to be taken from the paper by Xiang Sun and colleagues [1] on level of parental concern, socioeconomic status (SES) and risk of autism. Not only did the authors conclude that: "a higher SES was not associated with the risk of having ASC [autism spectrum conditions]" they also found that: "No child met ASC criteria where parents expressed no concerns".
Do you prefer "fashion victim" or "ensembly challenged"?

SES - including variables such as family income, parental educational attainment(s) and parental occupation(s) - has been something of a talking point in autism research down the years and the rather mixed messages which have come out of the research literature on SES and offspring autism risk (see here). The growing appreciation that children of those positioned in a higher SES bracket don't seem to be at any significantly greater risk of autism is something rather important as per other evidence, for example, noted by Fujiwara [2]. Whether this means previous contrary findings were in error or that there has been some shift in the factors linked to the onset of contemporary autism is unknown at this time.

Some of my first thoughts on the Sun SES findings were in relation to all the discussions about offspring autism potentially being associated with certain types of parental occupational choices [3]. Indeed, considering that the Sun study was both carried out in and originated from Cambridge (UK) and included Prof. Simon Baron-Cohen on the authorship team, it is coincidental that the findings could be construed as counter to such occupational links with autism (assuming that Physicists, Engineers and Mathematicians would be described as higher SES jobs).

Of course I'm not saying the research on any relationship between offspring autism and parental occupation choice is all bunk; the paper from Windham and colleagues [4] and other evidence is too strong to negate (including that of occupational exposures potentially being involved). Merely that there may be much more to see than just a spectrum of 'talent' genes overlapping with autism risk genes [5] when it comes to receipt of a diagnosis on the very wide autism spectrum. Oh, and assuming you believe talent is all in the genes...

The other finding from Sun et al discussing parental concern and potential diagnosis of autism in offspring also carries quite a bit of potential importance. Regular readers of this blog might already have picked up my respect for parents and carers as active agents both in terms of picking up the signs and symptoms of autism in their loved ones (see here) and also detecting and reporting other important comorbidity (see here). I see the Sun findings - "No child met ASC criteria where parents expressed no concerns" - as corroborating parents and caregivers as doing what they do best: knowing their own child. I might also suggest that the discussions on increasing autism rates solely being down to better awareness and greater diagnostic vigilance are not seemingly backed up by the Sun findings if we assume parental concerns represent the starting point of the diagnostic journey into autism.

Some music to close. Gershon Kingsley and Popcorn.


[1] Sun X. et al. Parental concerns, socioeconomic status, and the risk of autism spectrum conditions in a population-based study. Res Dev Disabil. 2014 Sep 25;35(12):3678-3688.

[2] Fujiwara T. Socioeconomic status and the risk of suspected autism spectrum disorders among 18-month-old toddlers in Japan: a population-based study. J Autism Dev Disord. 2014 Jun;44(6):1323-31.

[3] Baron-Cohen S. Does Autism Occur More Often in Families of Physicists, Engineers, and Mathematicians? Autism. 1998; 2: 296-301.

[4] Windham GC. et al. Autism spectrum disorders in relation to parental occupation in technical fields. Autism Res. 2009 Aug;2(4):183-91.

[5] Baron-Cohen S. Autism and the technical mind: children of scientists and engineers may inherit genes that not only confer intellectual talents but also predispose them to autism. Sci Am. 2012 Nov;307(5):72-5.

---------- Sun, X., Allison, C., Auyeung, B., Baron-Cohen, S., & Brayne, C. (2014). Parental concerns, socioeconomic status, and the risk of autism spectrum conditions in a population-based study Research in Developmental Disabilities, 35 (12), 3678-3688 DOI: 10.1016/j.ridd.2014.07.037

Tuesday, 21 October 2014

Antibiotics and childhood obesity: a weighty correlation

It's been a few weeks since the publication of the paper by L. Charles Bailey and colleagues [1] correlating early multiple exposure to broad spectrum antibiotics with obesity in infancy. On purpose I've left it a while before talking about this research so as to let the scientific dust settle a little and get a flavour for some of the discussions about this research (see here and see here).
You're a true vulgarian, aren't you?

A few details about the Bailey study first:

  • Looking at the electronic records for a large cohort of children (~65,000), researchers picked out "Treatment episodes for prescribed antibiotics" based on prescription data before the age of 2 years.
  • Anthropometric (growth) data was also determined from visits to healthcare providers between the ages of 2 and 5 years and compared with body mass index (BMI) norms derived from a large US-based survey, NHANES.
  • Results: "Sixty-nine percent of children were exposed to antibiotics before age 24 months" with a rough average of 2 antibiotic prescriptions per child. For those who received 4 or more courses of antibiotics, the risk of obesity during early childhood was slightly elevated (11%) compared with those receiving fewer courses.
  • The authors specifically focused on broad spectrum antibiotics as being correlated with infant weight issues; antimicrobials acting against a broad range of bacteria rather than more targeted pharmaceutics.
  • They concluded: "Repeated exposure to broad-spectrum antibiotics at ages 0 to 23 months is associated with early childhood obesity". That being said, they also noted that various other factors seemed to correlate with infant obesity including: "Steroid use, male sex, urban practice, public insurance, Hispanic ethnicity, and diagnosed asthma or wheezing".
  • I'm also minded to pull in a few other findings which did not get so many media headlines such as the reporting that at 4 years of age, 15% of the cohort were found to be obese and 33% overweight (source here).

The Bailey results are interesting insofar as the association being made between early antibiotic use and obesity but, as always, a little caution needs to be applied before reading too much into the findings. I note the BBC coverage of this article mentions limitations: "they were not able to look at the children's weight or exercise regimes" so correlation not necessarily being the same as causation comes into play. I might also add that whilst antibiotic stewardship is still a developing area, many/most antibiotic prescriptions are not just given willy-nilly as any parent with a young child suffering from an ear infection for example, will probably be able to attest.

I have kinda talked around this area of antibiotics and weight before on this blog (see here) and the implication that antibiotics, broad spectrum, by their very nature have a pretty profound effect on the trillions of bacterial beasties which inhabit places like the gastrointestinal (GI) tract. Carl Zimmer's post on swallowing a grenade (not literally) is a good starting point. The idea being that as well as helping digest our food, said bacteria (whether individual strains or through a more collective action) might also be able to influence a variety of issues like energy homoeostasis, weight management and even our risk of disease (see here and see here). If I take you back to some work looking at a particular bacterium called Akkermansia muciniphila you might get a flavour for this possible connection with weight in mind (at least in rodents).

I'm going to finish with another quote included with the BBC report on the Bailey findings. It comes from an independent commentary of the paper and sums up some important issues arising from reading this work:

"It would be a concern if parents took from this that they ought to be reluctant to allow antibiotic use in their children. The key risk factors for childhood obesity are over-consumption of high energy, nutrient-poor foods and lack of exercise."

Whilst I would perhaps suggest that 'energy in - energy out' is too simplistic an explanation of weight management issues (see here) I would agree that under the right circumstances, antibiotics still make a valuable contribution to the medicines cabinet, and obesity is, very much, a multi-faceted condition.

Music... Stevie Wonder and Superstition.


[1] Bailey LC. et al. Association of Antibiotics in Infancy With Early Childhood Obesity. JAMA Pediatr. 2014. 29 Sept.

---------- Bailey LC, Forrest CB, Zhang P, Richards TM, Livshits A, & DeRusso PA (2014). Association of Antibiotics in Infancy With Early Childhood Obesity. JAMA pediatrics PMID: 25265089

Monday, 20 October 2014

Reasons for visiting ER by those with autism

ER - Emergency Room - or as we call it here in Blighty Accident & Emergency (A & E), is never a particularly desirable place to visit given the emphasis on illness or injury of yourself or loved one. That being said, staff there do a sterling job sometimes under very stressful circumstances, responding to all-manner of complaints, some of which are life-threatening.

The paper by Dorothea Iannuzzi and colleagues [1] sought to identify some of the medical reasons why ER visits were made by people on the autism spectrum. They concluded that, depending on age, epilepsy or seizure-type disorders and "psychiatric conditions" were well represented in cases of autism based on data derived from the US 2010 National Emergency Department database.

Realising that epilepsy / seizure-type disorders seem to have more than a passing connection to quite a few cases of autism (see here) and can, in some cases, lead to that most extreme of outcomes (see here), I'm not going to focus any further on this part of the Iannuzzi findings. Rather the finding that: "Psychiatric conditions were primary among ASD individuals aged 12-15 years, accounting for more than 11 % of all visits" merits some further analysis.

The findings reported by Kalb and colleagues [2] documenting that: "Thirteen percent of visits among children with ASD [autism spectrum disorder] were due to a psychiatric problem, as compared with 2% of all visits by youths without ASD" provides further evidence for the extent of the Iannuzzi finding. Whilst treading carefully in this area of autism research, one detail stuck out from the Kalb report, whereby ER visits due to psychotic disorders seemed to be increased in likelihood compared to visits by asymptomatic children/youths. This seemed to tie in well with my recent discussions on the observations of Maibing and colleagues [3] and the risk/onset of schizophrenia spectrum disorders following a previous child or adolescent psychiatric diagnosis.

Unfortunately, my discussions on the research literature on ER visits and autism do not get any happier as I turn to the body of work looking at suicide attempts and autism, and as per the conclusion from Kato and colleagues [4], "ASDs should always be a consideration when dealing with suicide attempts in adults at the emergency room". Again, I've covered the very sensitive topic of suicide (ideation and attempts) and autism previously on this blog (see here and see here) and as we speak further research has emerged pertinent to this topic [5]. Though sometimes quite uncomfortable to discuss, this collected work emphasises how we all really need to be talking a lot more about this issue and what can be done to divert people away from this most extreme type of behaviour. Admission to the ER - which will often be the first point of contact after such behaviour - could be a good place to start having those discussions.

In amongst the literature talking about the ER and autism, there are other details which provide a rather more positive discussion about this topic. Take for example, the paper by Giarelli and colleagues [5] looking at the ways and means ER might be made more comfortable to [some of] those on the autism spectrum. Similarly, the guidance supplied by McGonigle and colleagues [6] talking about ways of managing agitation in the ER for those on the autism spectrum might also be better referenced in this clinical setting. Oh, and a bit more knowledge about medical comorbidities potentially affecting people with autism would probably not go amiss more generally.

I should conclude that whilst I've focused on some of the more frequently reported reasons why people with autism might present to the ER, one shouldn't forget that all the other reasons why the general population go to the ER are similarly as pertinent to those on the spectrum. That being said, I very much doubt that "help with removing false nails" would feature on most people's reasons to attend hospital...


[1] Iannuzzi DA. et al. Brief Report: Emergency Department Utilization by Individuals with Autism. J Autism Dev Disord. 2014 Sep 27.

[2] Kalb LG. et al. Psychiatric-related emergency department visits among children with an autism spectrum disorder. Pediatr Emerg Care. 2012 Dec;28(12):1269-76.

[3] Maibing CF. et al. Risk of Schizophrenia Increases After All Child and Adolescent Psychiatric Disorders: A Nationwide Study. Schizophr Bull. 2014 Sep 5. pii: sbu119.

[4] Kato K. et al. Clinical features of suicide attempts in adults with autism spectrum disorders. Gen Hosp Psychiatry. 2013 Jan-Feb;35(1):50-3.

[5] Takar K. & Kondo T. Comorbid atypical autistic traits as a potential risk factor for suicide attempts among adult depressed patients: a case–control study. Annals of General Psychiatry 2014, 13:33.

[6] Giarelli E. et al. Sensory stimuli as obstacles to emergency care for children with autism spectrum disorder. Adv Emerg Nurs J. 2014 Apr-Jun;36(2):145-63.

[7] McGonigle JJ. et al. Management of agitation in individuals with autism spectrum disorders in the emergency department. Child Adolesc Psychiatr Clin N Am. 2014 Jan;23(1):83-95.

---------- Iannuzzi DA, Cheng ER, Broder-Fingert S, & Bauman ML (2014). Brief Report: Emergency Department Utilization by Individuals with Autism. Journal of autism and developmental disorders PMID: 25261249

Saturday, 18 October 2014

More epigenetics, EN-2 and autism... the plot thickens

I don't mind admitting that I was to some extent 'winging it' with my previous post on epigenetics and Engrailed-2 (EN-2) as a consequence of the findings reported by Jill James and colleagues [1] with autism in mind. Although an avid follower of the science of epigenetics when (cautiously) applied to autism, I am by no means any authority on the subject matter particularly when it comes to the nitty-gritty details. You can probably therefore expect similar things in my latest discussions on yet more work from this research group which appeared recently [2].
I have only one rule. Everybody fights, no one quits.

And so, with that pinch of salt at the ready...

The final conclusion made in the most recent James article boils down to the suggestion that "persistent postnatal overexpression of EN-2 suggests that the closing of this programed developmental window may have been missed in some individuals with autism because of epigenetic abnormalities". That being said I think we have quite a way to come before we can substantiate this finding particularly when the main protagonist in the latest article is something called 5-hydroxymethylcytosine (5-hmC) and results which show "that elevated 5-hmC in the EN-2 promoter is associated with a significant decrease in repressive MeCP2 and histone H3K27me3 that appear to over-ride 5-mC hypermethylation". The H3K27me3 bit comes from their previous findings by the way.

To most readers that probably sounds as complicated as it first did to me so I will try and explain more.

EN-2 as I've talked about in that post on the previous James work, has been linked to cases of autism as per the example of the study by Wang and colleagues [3] linking mutations in this gene to cases of autism. The idea being that mice bred without the gene (the homeobox domain of EN2) show some of the [mouse] signs and symptoms of autism alongside issues with the cerebellum and a reduction in the number of Purkinje cells which have been previously noted in cases of autism [4]. The previous James results in this area reported on hypermethylation of the EN-2 promoter region which would normally equate as gene silencing in epigenetic terms, in line with the more structural genomic issues seen in autism that I've just talked about. But, and it is an important point, when they looked at EN-2 expression and protein levels - function and products of the gene - they actually found that levels were increased in their autism samples despite the methylation mark and its 'stop talking' properties. They noted on that occasion that "transcriptional upregulation by other epigenetic mechanisms predominated over the repressive tendencies of DNA cytosine methylation".

Their latest foray into this area sought to further clarify just what might be going on specifically with EN-2 gene-specific DNA hypermethylation previously reported. To do this they focused on both measuring 5-hmC and also 5-methylcytosine (5-mC) among other things based on the same tissue samples (post-mortem cerebellum samples) detailed in their previous study. 5-hmC is apparently an oxidation product of 5-mC mediated via something called TETs.

What they found, far from answering the question of a discrepancy between epigenetic gene silencing of EN-2 but increased gene function and products, actually makes the whole thing a lot more complicated. So they observed "a significant increase in both 5-mC and 5-hmC in the autism cerebellum relative to the control samples". Further that there was "a significant increase in 5-hmC content within the upstream EN-2 promoter region" and "a highly significant positive correlation... was found between 5-hmC content and EN-2 gene expression in the 5’ promoter CpG island in autism but not in control samples". They note that: "that 5-hmC accumulation is mechanistically related to gene upregulation" something which I think ties into other work hinting at the demethylating role for 5-hmC [5].

Insofar as my mention of MeCP2 and histone H3K27me3 from the latest and previous James reports, I can't really say too much more aside from noting again: "reduced MeCP2-mediated gene repression may have contributed to persistent EN-2 gene overexpression in the autism samples". Actually the authors speculate that MeCP2 binding and histone H3K27 trimethylation might work together in a "repressive" manner but when reduced as they were "may contribute to aberrant overexpression of EN-2 in the autism cerebellum" as per their findings.

I have to say that I struggled with getting my head around these findings and I'd quite understand if readers also struggled with my interpretation of them ("If you can't explain something to a six-year-old/granny, you really don't understand it yourself"). I understand that we don't all walk around with our genes stuck in the 'on' or 'off' position and that particularly during foetal and the early post-natal periods, genes are being switched on and off at a surprising rate for many, many different important reasons. I also understand that DNA methylation is an important part of the whole genes switched on or off thing but not the only way that this process can happen as per the authors mention of chromatin and some previous text in this area [6]. With my very limited knowledge of this area, I am however not yet convinced that we have the full story here; specifically in terms of why the original finding of hypermethylation of the EN-2 promotor region (gene silencing) yet increased expression and protein levels were reported. I wonder if indeed we might be able to learn more from a two-hit approach whereby hypermethylation of only one gene allele leaves the other still working?

Just before I finish I'd like to also draw your attention to another paper which has started to ask similar questions about 5-hmC and might be contrasted with the recent James paper. Zhubi and colleagues [7] (open-access here) looked at 5-hmC with a couple of other potentially important genes linked to cases of autism (RELN and GAD1) in mind. They reported: "a significant increase in TET1 expression and an enrichment in the level of 5-hmC... at the promoters of GAD1 and RELN in ASD when compared with CON [controls]". Further that their data are: "consistent with the hypothesis that an increase of 5-hmC (relative to 5-mC) at specific gene domains enhances the binding of MeCP2 to 5-hmC and reduces expression of the corresponding target genes in ASD [autism spectrum disorder] cerebella".

The plot thickens...

So then to some music... Hey Jude.


[1] James SJ. et al. Complex epigenetic regulation of Engrailed-2 (EN-2) homeobox gene in the autism cerebellum. Translational Psychiatry. 2013; 3: e232.

[2] James SJ. et al. Elevated 5-hydroxymethylcytosine in the Engrailed-2 (EN-2) promoter is associated with increased gene expression and decreased MeCP2 binding in autism cerebellum. Translational Psychiatry. 2014. 7 October.

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---------- James SJ, Shpyleva S, Melnyk S, Pavliv O, & Pogribny IP (2014). Elevated 5-hydroxymethylcytosine in the Engrailed-2 (EN-2) promoter is associated with increased gene expression and decreased MeCP2 binding in autism cerebellum. Translational psychiatry, 4 PMID: 25290267