Autism Spectrum Disorder

Motor delay - An early and more common "red flag" in girls rather than boys with autism spectrum disorder

BACKGROUND

Autism and intellectual disability may coincide and be preceded by global developmental delay or by motor delay.

HYPOTHESIS

Motor delay in the context of global developmental delay is an initial "red flag" for ASD, with added risk in girls.

OBJECTIVE

To assess early developmental milestones in girls with ASD as compared to diagnosed boys, considering prematurity risk.

METHOD

Developmental milestones in a cohort of 467 children with ASD - diagnosed at mean age of 3.4 years (SD = 2.2) - were analyzed according to gender and prematurity risk.

RESULTS

111 girls (24 %), 356 boys (76 %), presented with motor milestones acquisition grossly within the normal range. However, there was a shift towards acquisition of walking being at the later end of the norm range, with this shift being more prominent in girls. 60 % of girls and 47 % of boys with ASD had motor delay and 49 % of girls and 36 % of boys had global developmental delay. The extent of the delays was greater in the prematurity subgroup.

CONCLUSION

Global delay of early milestones occurred in half of children with ASD and in 60 % of girls with ASD. Delayed acquisition of independent walking is relatively more common in girls subsequently diagnosed with ASD.

Carbohydrate Scaffolds for the Study of the Autism-associated Bacterium, Clostridium bolteae

A large number of children in the autism spectrum disorder suffer from gastrointestinal (GI) conditions, such as constipation and diarrhea. Clostridium bolteae is a part of a set of pathogens being regularly detected in the stool samples of hosts affected by GI and autism symptoms. Accompanying studies have pointed out the possibility that such microbes affect behaviour through the production of neurotoxic metabolites in a so-called, gut-brain connection. As an extension of our Clostridium difficile polysaccharide (PS)-based vaccine research, we engaged in the discovery of C. bolteae surface carbohydrates. So far, studies revealed that C. bolteae produces a specific immunogenic PS capsule comprised of disaccharide repeating blocks of mannose (Manp) and rhamnose (Rhap) units: α-D-Manp-(1→[-4)-β-D-Rhap- (1→3)-α-D-Manp-(1→]n. For vaccinology and further immunogenic experiments, a method to produce C. bolteae PS conjugates has been developed, along with the chemical syntheses of the PS non-reducing end linkage, with D-Rha or L-Rha, α-D-Manp-(1→4)-α-D-Rhap- (1→O(CH2)5NH2 and α-D-Manp-(1→4)-α-L-Rhap-(1→O(CH2)5NH2, equipped with an aminopentyl linker at the reducing end for conjugation purposes. The discovery of C. bolteae PS immunogen opens the door to the creation of non-evasive diagnostic tools to evaluate the frequency and role of this microbe in autistic subjects and to a vaccine to reduce colonization levels in the GI tract, thus impeding the concentration of neurotoxins.

Advances in Tuberous Sclerosis Complex (TSC) research

Purpose

– The purpose of this paper is to provide a brief, descriptive overview of Tuberous Sclerosis Complex (TSC) research with particular reference to studies on Autism Spectrum Disorder (ASD).

Design/methodology/approach

– A search of electronic databases was carried out to identify English language articles on TSC. The literature was explored in more detail with a focus on neurodevelopmental disorders associated with TSC such as ASD.

Findings

– The review included 3,679 references. The earliest articles identified were published in the early twentieth century. Since then research on TSC has advanced rapidly and is being carried out worldwide. Just 62 studies have focused on ASD in TSC, although the number of publications is increasing over time.

Research limitations/implications

– More research on ASD in TSC is needed to benefit those affected by TSC and the broader ASD scientific community.

Practical implications

– Practitioners working with children and adults with ASD should be aware of the wider health issues experienced by those with genetic conditions such as TSC. Similarly, clinicians working with those who have TSC should be aware of the high prevalence of ASD in the group and implications for the way they work with their patients.

Originality/value

– This is the first paper to map and characterise the scientific literature on TSC. There remains a focus on the biomedical aspects of TSC with fewer studies on psychosocial/educational or family impacts. The review concludes with recommended research questions for the future.