The microbiome in Asperger syndrome: A pilot study

Autism is a well-known behavioural characteristic which has a high prevalence
in individuals with intellectual disability. Autism that goes along with
intellectual disability is known to have a very large number of causes,
especially chromosome imbalances and changes in Mendelian genes. Asperger
syndrome is characterized by autism but with near-typical language development
and without intellectual disability. Studies to detect causes of Asperger
syndrome have invariably failed to show abnormalities; especially no chromosome
anomalies or mutations in Mendelian genes can be detected. This indicates there
may be non-genetic causes. We suggest here that one of the causative factors
may be a disturbance in the gut microbiome. There is growing evidence of a
strong brain-gut axis, and an association between the gut microbiome and
behaviour. Several small studies have indicated that individuals with autism
plus intellectual disability can have a microbiome that differs from the
microbiome in neurotypical individuals. To date, no microbiome studies have
been done in individuals with Asperger syndrome however.

The way a gut-brain axis functions is at present unknown. We suggest the
*transport* of microbiome information works through thrombocytes, and that
there is a local action through a change in the methylation status of brain
cells.

The primary objective is determining whether there is a difference in faecal
microbiome constitutions in individuals with Asperger syndrome compared to
their non-affected sibs. The secondary objectives are whether there is a
correlation between microbial DNA in thrombocytes and the microbiome. We will
also investigate whether this is influenced by the diet.

Pilot case-control study

The burden of registering the normal diet of participants for 2 days represents
a negligible burden and also the single harvesting of faeces, performed at
home, is no burden. Only the blood sampling is a burden especially in the
children aged 12-18years. We have considered performing the study in adults
only. However we reasoned that irrespective the results in adults this study
needs to be performed in children as well, as it remains uncertain whether
results in adults can be translated to the paediatric group and vice versa. As
a single blood sampling in the group 12-18years is still a limited burden, and
as the study has the potential to offer a significant benefit to the group of
children with Asperger as a whole, we considered it acceptable to perform the
study in children.