Combining multivariate genomic approaches to elucidate the comorbidity between autism spectrum disorder and attention deficit hyperactivity disorder

J Child Psychol Psychiatry. 2021 Nov;62(11):1285-1296. doi: 10.1111/jcpp.13479. Epub 2021 Jul 7.

Abstract

Background: Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are two highly heritable neurodevelopmental disorders. Several lines of evidence point towards the presence of shared genetic factors underlying ASD and ADHD. We conducted genomic analyses of common risk variants (i.e. single nucleotide polymorphisms, SNPs) shared by ASD and ADHD, and those specific to each disorder.

Methods: With the summary data from two GWAS, one on ASD (N = 46,350) and another on ADHD (N = 55,374) individuals, we used genomic structural equation modelling and colocalization analysis to identify SNPs shared by ASD and ADHD and SNPs specific to each disorder. Functional genomic analyses were then conducted on shared and specific common genetic variants. Finally, we performed a bidirectional Mendelian randomization analysis to test whether the shared genetic risk between ASD and ADHD was interpretable in terms of reciprocal relationships between ASD and ADHD.

Results: We found that 37.5% of the SNPs associated with ASD (at p < 1e-6) colocalized with ADHD SNPs and that 19.6% of the SNPs associated with ADHD colocalized with ASD SNPs. We identified genes mapped to SNPs that are specific to ASD or ADHD and that are shared by ASD and ADHD, including two novel genes INSM1 and PAX1. Our bidirectional Mendelian randomization analyses indicated that the risk of ASD was associated with an increased risk of ADHD and vice versa.

Conclusions: Using multivariate genomic analyses, the present study uncovers shared and specific genetic variants associated with ASD and ADHD. Further functional investigation of genes mapped to those shared variants may help identify pathophysiological pathways and new targets for treatment.

Keywords: Autism spectrum disorder; GWAS; SNP; attention deficit hyperactivity disorder; colocalization; common genetic variants; comorbidity; genomic structural equation modelling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Attention Deficit Disorder with Hyperactivity* / epidemiology
  • Attention Deficit Disorder with Hyperactivity* / genetics
  • Autism Spectrum Disorder* / epidemiology
  • Autism Spectrum Disorder* / genetics
  • Comorbidity
  • Genome-Wide Association Study
  • Genomics
  • Humans
  • Paired Box Transcription Factors / genetics
  • Polymorphism, Single Nucleotide
  • Repressor Proteins / genetics

Substances

  • Paired Box Transcription Factors
  • Repressor Proteins
  • PAX1 transcription factor
  • INSM1 protein, human