Autism is a condition which is exclusively defined by the presence of various behaviours combined with an analysis of developmental history. There is no genetic or biological test currently available to provide objective confirmation on the presence or not of autism.
That is not to say however, that there may not be clues as to the genetic or biological underpinnings of autism based on the presence of autism or autistic-like presentation in other defined conditions with better categorised origins and pathology.
One example of such a condition is that of 22q11.2 deletion syndrome (Del22). Del22 is a genetic disorder characterised by the deletion of a small piece of chromosome 22 at a location called q11.2. People with Del22 can present with various signs and symptoms affecting physical health including heart problems and issues with immune function. Corresponding developmental issues manifesting as behavioural or learning difficulties are also frequently reported including the presence of autism or autistic like behaviours.
There has been some debate in autism research circles about the presentation of autism in people subsequently diagnosed with Del22 and how those with Del22 may present with a subtly different type of autism from non-Del22 cases. Nevertheless, there is continued interest in the connection between Del22 and the presentation of autism.
The paper by Giardino and colleagues* adds a further layer of complexity to the presentation of Del22 with their observations of gastrointestinal (GI) symptoms potentially being a common issue in the condition.
Reporting on a small number of patients diagnosed with Del22, researchers used a battery of physiological tests to assess GI functions. They reported that over half of their patients presented with some kind of GI issue, many of them reporting functional bowel issues such as constipation and abdominal pain. Further, they reported secondary physical signs of potential GI issues according to weight deficiency and failure to thrive in their cohort. Coeliac disease, an autoimmune condition linked to issues with the protein gluten, was confirmed in one patient but others presented with immunological signs of reactivity to gluten (removal of which is the main treatment for coeliac disease). The authors conclude that further research on the GI manifestations noted in cases of Del22 might offer further strategies to help patients manage their condition.
The presentation of autism or autistic-like behaviours in Del22 alongside GI involvement in at least some cases offers further clues for autism research too. Whilst GI issues are not a universal part of the presentation of autism, nor exclusive to autism, the suggestion that genetic issues may influence both behaviour and physiology, including GI physiology, is an interesting one. This, particularly in light of a growing body of research indicating that various GI issues may be an over-represented comorbidity when examined with autism in mind.
* Giardino G. et al. Gastrointestinal involvement in patients affected with 22q11.2 deletion syndrome. Scand J Gastroenterol. 2013 Dec 18.
Further commentary on this study can be found at: http://questioning-answers.blogspot.com/2014/01/the-gut-and-22q112-deletion-syndrome.html