Maintenance of Heterochromatin links Chromatin Modifiers and Neurodevelopment in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a highly heritable and highly heterogeneous neuropsychiatric condition whose cause is still unknown because there are no recurrent genes found among diagnosed individuals. One of the most common functional properties of the many reported risk-genes for autism is “chromatin modification” but it is not known how this biological process relates to neurodevelopment and autism. We recently reported frequent, recurrent genomic structural variants (SVs) in two cohorts of individuals with autism that were identified using non-Mendelian inheritance (NMI) patterns in family trios. The genes harboring the SVs participate in neurodevelopment, glutamate signaling, and chromatin modification, confirming previous reports and providing greater detail for these processes in ASD. The majority of these ASD-associated SVs (ASD-SV) were found in non-coding regions of the genome and were enriched for expression quantitative trait loci (eQTL) suggesting that gene dysregulation results from these genomic disruptions rather than alteration of proteins. Here, we intersect the ASD-SV from our earlier work with different gene regulatory and epigenetic multiomic layers to understand how they may function to produce autism. Our results indicate that the core of ASD resides in the dysregulation of a process called RNA-induced Initiation of Transcriptional gene Silencing (RITS) that is meant to maintain heterochromatin and produces SVs in the genes within these chromosomal regions, resulting in alterations in brain development. This finally links reported ASD-risk genes involved in chromatin remodeling with neurodevelopment. In addition, it may explain the role of de novo mutations in ASD and provide a framework for more accurate diagnostics and endophenotypes. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Funding was from the Laboratory Directed Research & Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LCC for the US Department of Energy. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study used information from previously published research openly available to the public. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data are included in the upload of this manuscript. Original data are online or available from the NIH database of genotypes and phenotypes.