Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) share certain genetic variants and genes. Additional research focused on these variants may help identify pathophysiological pathways and new treatment targets for these disorders, according to research findings published in the Journal of Child Psychology and Psychiatry.
A team of researchers performed genomic analyses, including genomic structural equation modelling and colocalization analysis, of summary data from genome-wide association studies (GWAS) on ASD (n=46,350) and ADHD (n=55,374). They sought to identify single nucleotide polymorphisms (SNPs) shared by the 2 disorders as well as SNPs specific to each.
In the colocalization analyses, the researchers found 37.5% of SNPs of ASD colocalized with SNPs of ADHD (P <1e-6). Additionally, approximately 19.6% of SNPs of ADHD colocalized with SNPs of ASD (P <1e-6).
The study researchers applied FUMA (Functional Mapping and Annotation of GWAS) to the SNPs colocalized between ADHD and ASD, which prioritized 6 genes previously reported in other studies: XRN2, SORCS3, PTBP2, NKX2-4, MANBA, and DPYD. Another 2 novel genes, INSM1 and PAX1, were also found.
A bidirectional Mendelian randomization analysis found an association between the risk of ASD and an increased risk of ADHD (β–MR-IVW = 0.51 (0.09); P <.001; n of SNPs, 15). In the reverse direction, the study researchers found an association between the risk of ADHD and an increased risk of ASD (β–MR-IVW = 0.33 (0.05); P <.001; n of SNPs, 40).
Regarding study limitations, the investigators noted that sample overlap in controls may have introduced bias in the findings.
Given the study’s findings, the researchers suggested additional “investigation of the shared and specific genetic factors of neurodevelopmental disorders may help identify pathophysiological pathways and new targets for treatment” of patients with ASD and ADHD.
Peyre H, Schoeler T, Liu C, et al. Combining multivariate genomic approaches to elucidate the comorbidity between autism spectrum disorder and attention deficit hyperactivity disorder. Published online July 7, 2021. J Child Psychol Psychiatry. doi:10.1111/jcpp.13479