De Novo Insertions and Deletions of Predominantly Paternal Origin Are Associated with Autism Spectrum Disorder

• De novo frameshift indels are associated with ASD with an odds ratio of 1.6
• Multiple de novo indels in KMT2E and RIMS1 implicate these genes in ASD
• 88% of de novo indels arise on the paternal chromosome
• Synaptic function, chromatin modification, and FMRP targets play key roles in ASD

SummaryWhole-exome sequencing (WES) studies have demonstrated the contribution of de novo loss-of-function single-nucleotide variants (SNVs) to autism spectrum disorder (ASD). However, challenges in the reliable detection of de novo insertions and deletions (indels) have limited inclusion of these variants in prior analyses. By applying a robust indel detection method to WES data from 787 ASD families (2,963 individuals), we demonstrate that de novo frameshift indels contribute to ASD risk (OR = 1.6; 95% CI = 1.0–2.7; p = 0.03), are more common in female probands (p = 0.02), are enriched among genes encoding FMRP targets (p = 6 × 10−9), and arise predominantly on the paternal chromosome (p < 0.001). On the basis of mutation rates in probands versus unaffected siblings, we conclude that de novo frameshift indels contribute to risk in approximately 3% of individuals with ASD. Finally, by observing clustering of mutations in unrelated probands, we uncover two ASD-associated genes: KMT2E (MLL5), a chromatin regulator, and RIMS1, a regulator of synaptic vesicle release.

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