Integrative Analysis Prioritized Molecular Biomarkers Associated With The Etiology Of Neurodevelopmental Disorders

Background:Neurodevelopmental disorders(NDDs)are a set of complex disorders characterized by diverse and co-occurring clinical symptoms consisting of autism spectrum disorder(ASD),Schizophrenia(SCZ),intellectual disability(ID)and epileptic encephalopathy(EE).The contribution of rare genetic variations in patients with NDDs remains largely unknown.ASD is a neurodevelopmental disorder with high phenotypic and genetic heterogeneity.The high heterogeneity of ASD leads to the lacking of effective options for its treatment.The common variants of specific oxytocin-related genes(OTRGs),particularly OXTR,are associated with the ASD etiology.And some genome-wide association studies have attempted to link these common variants to the efficacy of oxytocin intervention in ASD,findings are paradoxical.Rare genetic variation is known risk factor for NDDs.Therefore,we hypothesized that the intervention effect of oxytocin in ASD may be largely dependent on these rare genetic variants.Purpose:The aim of this study is to systematically investigate the contribution of rare genetic variations to NDDs,and to further explore the association between rare genetic variations in OTRGs and ASD etiology.Finally,it is hoped that this study will assisting the clinical research of precise intervention of oxytocin in ASD.Methods:Firstly,we sequence 519 NDD-related genes in 3195 Chinese probands with neurodevelopmental phenotypes.Meanwhile,the de novo mutations(DNMs)of 16807 probands with NDDs are retrieved from public datasets and combine in an integrated analysis with the mutation data of our Chinese NDD probands by taking 3582 in-house Chinese controls as background to identify the risk genes for NDDs.The functions of the new candidate genes,which screened by collected known risk genes were explored by combining public brain expression,protein-protein interaction and brain differential expression between patients and normal controls.Furthermore,we curated 963 OTRGs and cataloged publicly available DNMs from 6511 ASD patients and 3391 controls,rare inherited variants(RIVs)from 1786 ASD patients and controls,as well as both de novo copy number variations(dnCNVs)and inherited CNVs(ihCNVs)form 15581 ASD patients and 6017 controls.Then,mutation burden and association analysis were used to explore the contribution of these variations in OTRGs to ASD pathology,respectively.An integrated model was designed to evaluate the contribution of genes to ASD etiology and further identify the positively contributed genes.Results:We identified 2522 putative functional mutations in Chinese NDD patients consisting of 137 DNMs in 86 genes and 2385 RIVs and inheriance state unkonwn variants with 22 X-linked hemizygotes in 13 genes,2 homozygous mutations in 2 genes and 23 compound heterozygous mutations in 10 genes.Furthermore,we prioritize 26 novel candidate genes.Notably,six of these genes-ITSN1,UBR3,CADM1,RYR3,FLNA,and PLXNA3-preferably contribute to ASD,as demonstrated by high coexpression and/or interaction with ASD genes confirmed via rescue experiments in a mouse model.Importantly,these genes are differentially expressed in the ASD cortex in a significant manner and involved in ASDassociated networks.In addition,the rare genetic variations of OTRGs were significantly associated with ASD etiology,in the order of dnCNVs>ihCNVs>DNMs,at the individual level.Furthermore,172 OTRGs and their connected 286 ASD core genes were prioritized to contribute to ASD etiology positively,including top ranked mitogen-activated protein kinases 3(MAPK3).Overall,rare disruptive genetic variations in 172 OTRGs and their connected 286 ASD core genes(oxytocin-related biomarkers)are associated with ASD etiology.Conclusions:This study expands the genetic spectrum of Chinese NDDs,further identified candidates may assist the early diagnosis of NDDs.In addition,oxytocin-related biomarkers identified herein could be valuable in both understanding the underlying mechanism of ASD pathophysiology and clinical investigation of ASD intervention with oxytocin.