Meta-analysis of GWAS of over 16,000 individuals with autism spectrum disorder highlights a novel locus at 10q24.32 and a significant overlap with schizophrenia

Background: Over the past decade genome-wide association studies (GWAS) have been applied to aid in theunderstanding of the biology of traits. The success of this approach is governed by the underlying effect sizes carriedby the true risk variants and the corresponding statistical power to observe such effects given the study design andsample size under investigation. Previous ASD GWAS have identified genome-wide significant (GWS) risk loci; however,these studies were of only of low statistical power to identify GWS loci at the lower effect sizes (odds ratio (OR) <1.15).Methods: We conducted a large-scale coordinated international collaboration to combine independent genotypingdata to improve the statistical power and aid in robust discovery of GWS loci. This study uses genome-widegenotyping data from a discovery sample (7387 ASD cases and 8567 controls) followed by meta-analysis of summarystatistics from two replication sets (7783 ASD cases and 11359 controls; and 1369 ASD cases and 137308 controls).Results: We observe a GWS locus at 10q24.32 that overlaps several genes including PITX3, which encodes a transcriptionfactor identified as playing a role in neuronal differentiation and CUEDC2 previously reported to be associated with socialskills in an independent population cohort. We also observe overlap with regions previously implicated in schizophreniawhich was further supported by a strong genetic correlation between these disorders (Rg = 0.23; P=9 ×10−6). We furthercombined these Psychiatric Genomics Consortium (PGC) ASD GWAS data with the recent PGC schizophrenia GWAS toidentify additional regions which may be important in a common neurodevelopmental phenotype and identified 12novel GWS loci. These include loci previously implicated in ASD such as FOXP1 at 3p13, ATP2B2 at 3p25.3, and a‘neurodevelopmental hub’ on chromosome 8p11.23.Conclusions: This study is an important step in the ongoing endeavour to identify the loci which underpin the commonvariant signal in ASD. In addition to novel GWS loci, we have identified a significant genetic correlation with schizophreniaand association of ASD with several neurodevelopmental-related genes such as EXT1, ASTN2, MACROD2, and HDAC4.Keywords: Autism spectrum disorder, Genome-wide association study, Meta-analysis, Genetic correlation, Heritability,Gene-set analysis, Schizophrenia, Neurodevelopment