Host genetics influences the relationship between the gut microbiome and psychiatric disorders.

The gut microbiome is associated with psychiatric disorders; however, the molecular mechanisms mediating this association are poorly understood. The ability of host genetics to modulate the gut microbiome may be an important factor in understanding the association. In this study, we aimed to evaluate the role of genetic variants associated with the gut microbiome in the susceptibility of individuals to four psychiatric disorders: schizophrenia (SCZ), attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and major depressive disorder (MDD). A total of 201 host genetic markers associated with microbiome outcomes and reported in available genome-wide association studies (GWAS) were included in the analyses. We searched for these variants in the summary statistics of the largest GWAS on these disorders to date, which were published by the Psychiatric Genomic Consortium, and performed gene-based and gene set association analyses. Two variants were significantly associated with ASD (rs9401458 and rs9401452) and one with MDD (rs75036654). For the gene-based association analysis, eight genes were associated with SCZ (ASIC2, KCND3, ITSN1, SIPA1L3, RBMS3, BANK1, CSMD1, and LHFPL3), one with MDD (ACTL8), two with ADHD (C14orf39 and FBXL17), and one with ASD (PINX). The gene set comprising 83 genes was associated with SCZ (p = 0.047). These findings suggest that genes related to microbiome composition may affect the susceptibility of individuals to psychiatric disorders, mainly schizophrenia. Although less robust, the associations with ASD, ADHD, and MDD cannot be discarded.