Protein-Altering Variants' Analysis in Autism Subgroups Uncovers Early Brain-Expressed Gene Modules Relevant to...

Area of Science:

• Genetics
• Neuroscience
• Developmental Biology

Background:

• Autism spectrum disorder (ASD) presents significant heterogeneity, making it challenging to understand the functional impact of genetic variants.
• Gene set analysis offers a method to assess the cumulative effects of functionally related genes.
• Identifying specific gene sets associated with different phenotypic presentations in ASD is crucial for understanding its underlying biology.

Purpose of the Study:

• To investigate whether a multi-step gene set analysis can identify distinct patterns of protein-altering variants (PAVs) between subgroups of autistic children with varying intelligence quotients (IQ).
• To explore the functional relevance and developmental expression of identified gene sets and modules in the human brain.
• To assess the enrichment of known autism susceptibility genes within these identified gene modules.

Main Methods:

• Subdivided autistic children (n=71) into higher (>80) and lower (≤80) IQ groups.
• Performed gene set variant enrichment analysis to compare PAV incidence between subgroups.
• Clustered significant gene sets into modules, investigated brain expression using the BrainSpan Atlas, and extended modules via spatio-temporal co-expression and physical interactions.
• Examined the prevalence of autism susceptibility genes within original and extended modules.

Main Results:

• Identified 38 significant gene sets (FDR, q<0.05) clustering into four modules associated with ion cell communication, neurocognition, gastrointestinal function, and the immune system.
• These modules exhibited specific spatio-temporal expression patterns in the developing human brain.
• Extended gene modules revealed an over-representation of autism susceptibility genes, suggesting their functional relevance.

Conclusions:

• The study successfully identified functionally relevant gene modules implicated in autism pathophysiology and phenotypic variability.
• The findings support the hypothesis that autism's diversity arises from multiple interacting genetic pathways.
• This unbiased, multi-step approach provides a framework for identifying genetic pathways crucial for autism subtyping and understanding its heterogeneity.