Disruptive CHD8 mutations define a subtype of autism early in development

Area of Science:

• Genetics
• Neurodevelopmental Disorders
• Developmental Biology

Background:

• Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with significant heterogeneity.
• Behavioral approaches to subtype identification in ASD have yielded limited success.
• Genetic factors are increasingly recognized as crucial in understanding ASD etiology.

Purpose of the Study:

• To investigate the role of the CHD8 gene in identifying genetically distinct subtypes of ASD.
• To characterize the phenotypic features associated with CHD8 mutations in individuals with developmental delay or ASD.

Main Methods:

• Resequencing of the ASD-associated gene CHD8 in a cohort of 3,730 children with developmental delay or ASD.
• Mutation analysis comparing affected individuals with a control group of 8,792 individuals, including unaffected siblings.
• Phenotypic characterization of individuals with identified CHD8 mutations.
• Functional studies using zebrafish models to recapitulate human phenotypes.

Main Results:

• Fifteen independent mutations in the CHD8 gene were identified in the study cohort.
• No truncating CHD8 mutations were found in the control group, indicating a strong association.
• Individuals with CHD8 mutations showed a high likelihood of ASD diagnosis and were enriched for macrocephaly, distinct facial features, and gastrointestinal complaints.
• Zebrafish models with disrupted CHD8 exhibited enlarged head size and impaired gastrointestinal motility, mirroring human symptoms.

Conclusions:

• Disruptions in the CHD8 gene define a specific subtype of autism spectrum disorder.
• CHD8 mutations highlight a link between brain development and enteric nervous system function.
• This research provides a genetic basis for a distinct ASD subtype and reveals novel comorbidities.