Refining the scope of genetic influences on alcohol misuse through environmental stratification and gene-environment interaction

Abstract

AbstractBackgroundGene-environment interaction (G×E) is likely an important influence shaping individual differences in alcohol misuse (AM), yet it has not been extensively studied in molecular genetic research. In this study, we utilize a series of genome-wide gene-environment interaction (GWEIS) andin silicoannotation methods with the aim of improving gene identification and biological understanding of AM.MethodsWe carried out GWEIS for four AM phenotypes in the large UK Biobank sample (N= 360,314), with trauma exposure and socioeconomic status (SES) as moderators of the genetic effects. Exploratory analyses compared stratified GWAS and GWEIS modelling approaches. We applied functional annotation, gene- and gene-set enrichment, and polygenic score analyses to interpret the GWEIS results.ResultsGWEIS models showed few genetic variants with significant interaction effects across all gene-environment pairs. Enrichment analyses identified moderation by SES of the genesNOXA1,DLGAP1, andUBE2L3,on drinking quantity and the geneIFIT1Bon drinking frequency. Except forDLGAP1, these genes have not previously been linked to AM. The most robust results (GWEIS interactionp= 4.59e-09) were seen for SES moderating the effects of variants linked to immune-related genes on a pattern of drinking with versus without meals.ConclusionsEven in large samples, G×E effects are difficult to detect at the molecular level. Our results highlight several genes and a potential mechanism of immune system functioning behind the moderating effect of SES on the genetic influences on AM. While GWEIS seems to be a preferred approach over stratified GWAS, modelling molecular G×E effects remains a challenge that will require larger consortia and more in-depth phenotypic measurement.