Parallel Single-Tissue Summary-Data Mendelian Randomization and Functional Validation Identify the ARRDC1 Promoter...

Anxiety disorders are highly heritable, but their underlying genetic mechanisms remain poorly understood. This study aimed to identify and functionally characterize genes whose expression is causally linked to anxiety disorder risk by integrating the parallel single-tissue genetic data.

We applied a parallel single-tissue summary-data-based Mendelian randomization (SMR) approach. This integrated large-scale anxiety disorder GWAS statistics with expression quantitative trait loci (eQTL) data from peripheral blood and 13 brain regions. The functional impact of a prioritized SNP (rs4494021) was tested via dual-luciferase reporter assay. The behavioral consequences were investigated by performing stereotaxic, lentivirus-mediated overexpression of ARRDC1 specifically in the mouse cerebellar hemisphere, followed by comprehensive behavioral testing.

The SMR analysis identified thirteen potential causal genes (ITIH3, ZKSCAN4, GNL3, SLC35C1, FNBP4, COPZ1, ATP5MC1, ITIH4, EHMT1, PTPMT1, ARRDC1, NEK4, and BTN3A2). Among them, ARRDC1 emerged as a significant gene, showing associations with anxiety disorders in blood, cerebellar hemisphere, and cerebellum. The risk allele of the promoter SNP rs4494021 significantly enhanced ARRDC1 transcriptional activity. Crucially, cerebellar overexpression of ARRDC1 in mice robustly induced anxiety-like behaviors, including reduced exploration in the open field test, decreased open-arm activity in the elevated plus maze, and increased avoidance in the light-dark box test.

By bridging genetic epidemiology with molecular and behavioral validation, this study identifies ARRDC1 promoter SNP rs4494021 as a genetically associated marker for anxiety disorders and functionally validates that elevated cerebellar ARRDC1 expression contributes to anxiety pathogenesis. These findings establish ARRDC1 as a functionally supported risk gene and highlight a novel component of anxiety-related neurocircuitry.