Homozygous deletions implicate non-coding epigenetic marks in Autism spectrum disorder

Area of Science:

• Genetics
• Genomics
• Neuroscience

Background:

• Most of the human genome is non-coding DNA, yet its role in disease is understudied.
• Autism Spectrum Disorder (ASD) is primarily linked to coding gene variations, leaving many cases genetically undiagnosed.

Purpose of the Study:

• To investigate the role of non-coding DNA variations, specifically biallelic copy number variations (CNVs), in Autism Spectrum Disorder (ASD).
• To identify novel non-coding mechanisms contributing to ASD etiology.
• To develop methods for identifying critical non-coding regulatory regions in the human genome.

Main Methods:

• Analysis of 187 consanguineous families with ASD for biallelic CNVs.
• Assessing the overlap of deletions with regulatory elements using ENCODE histone peak data.
• Comparing deletion overlap with regulatory regions using the Roadmap Epigenomics 127-epigenome dataset.

Main Results:

• Recessive deletions were significantly enriched in individuals with ASD compared to unaffected siblings (17% vs. 4%).
• Most identified biallelic deletions did not disrupt coding exons but overlapped with regulatory regions.
• Enrichment of deletions was observed in enhancers within brain tissue and neuronal progenitor cells.

Conclusions:

• Non-coding DNA deletions, particularly in regulatory regions, represent a novel mechanism contributing to ASD.
• The study presents a robust method for pinpointing functionally significant non-coding genomic regions.
• Gene regulation and activation are highlighted as potentially crucial factors in cognitive and social development relevant to ASD.