Despite an estimated twin heritability of ~50%, genome-wide association studies (GWAS) of opioid use disorder (OUD) have revealed few genome-wide signi cant (GWS) loci, with replicated ndings only in European-ancestry individuals. To identify novel loci, including those in non-European ancestries, and improve our understanding of the biology of OUD, we conducted a cross-ancestry meta-analysis using the Million Veteran Program (MVP). OUD cases in MVP had at least 1 International Classi cation of Diseases (ICD)-9 or ICD-10 code for opioid abuse or dependence (N=31,473). Opioid-exposed controls (N=394,471) had one or more outpatient opioid prescription lls. We conducted GWAS for each major ancestral group in MVP: African Americans (AAs; N=88,498), European Americans (EAs; N=302,585), and Hispanic Americans (HAs; N=34,861), followed by a cross-ancestry meta-analysis. Ten loci were GWS in the cross-ancestry meta-analysis, 8 of them novel. In addition to the known coding variant rs1799971 in OPRM1, which was the lead SNP genome-wide (p=6.78x10 −10 ), and a recently reported exonic variant in FURIN, we identi ed intronic variants in RABEPK, FBXW4, NCAM1, and KCNN1. Ancestry-speci c analyses identi ed an additional novel locus for each of the 3 ancestry groups. A supplementary meta-analysis within EAs that included MVP and other samples identi ed a locus in TSNARE1, which was also GWS in the cross-ancestry meta-analysis of all datasets. Gene-based association analyses identi ed 1 gene in AAs (CHRM2) and 3 in EAs (OPRM1, DRD2, and FTO). Signi cant genetic correlations (r g 's) were identi ed for 127 traits, including positive correlations with schizophrenia, problematic alcohol use, and major depressive disorder. The most signi cantly enriched cell type group was the central nervous system with gene-expression enrichment identi ed in brain regions previously associated with substance use disorders. With a case sample 50% larger than that of the previous largest GWAS, we identi ed 14 loci for OUD, including 12 novel loci, some of which were ancestry speci c. These ndings increase our understanding of the biological pathways involved in OUD, which can inform preventive, diagnostic, and therapeutic efforts and thereby help to address the opioid epidemic. Revision (ICD-10) diagnosis of OUD and control subjects were opioid exposed. Further details on phenotyping are described below. This GWAS was used for all subsequent downstream analyses.In a supplementary analysis, we performed within-ancestry meta-analyses for AAs and EAs from the MVP, Yale-Penn

Recent GWAS of alcohol-related traits have uncovered key differences in the underlying genetic architectures of alcohol consumption and alcohol use disorder (AUD), with the two traits having opposite genetic correlations with psychiatric disorders. Understanding the genetic factors that underlie the transition from heavy drinking to AUD has important theoretical and clinical implications. We utilized longitudinal data from the cross-ancestry Million Veteran Program sample to identify 1) novel loci associated with AUD and alcohol consumption [measured by the Alcohol Use Disorders Identification Test-Consumption (AUDIT-C)] and 2) genetic variants with direct effects on AUD not mediated through alcohol consumption. We identified 26 loci associated with AUD, including 5 ancestry-specific and 6 novel loci and 22 loci associated with AUDIT-C, including 3 ancestry-specific and 8 novel loci. In secondary GWAS that excluded individuals who report abstinence, we identify 7 additional loci for AUD and 8 additional loci for AUDIT-C. We demonstrate that, although the heterogeneity of the abstinent group biases the GWAS findings, unique variance between alcohol consumption and disorder remains after the group is excluded. Finally, using mediation analysis, we identified a set of variants with effects on AUD that are not mediated through alcohol consumption. The distinct genetic architectures of alcohol consumption and AUD suggest different biological contributions to the traits. Genetic variants with direct effects on AUD are potentially relevant to understanding the transition from heavy alcohol consumption to AUD and targets for translational prevention and treatment efforts.

Despite an estimated twin heritability of ~50%, genome-wide association studies (GWAS) of opioid use disorder (OUD) have revealed few genome-wide significant (GWS) loci, with replicated findings only in European-ancestry individuals. To identify novel loci, including those in non-European ancestries, and improve our understanding of the biology of OUD, we conducted a cross-ancestry meta-analysis using the Million Veteran Program (MVP). OUD cases in MVP had at least 1 International Classification of Diseases (ICD)-9 or ICD-10 code for opioid abuse or dependence (N=31,473). Opioid-exposed controls (N=394,471) had one or more outpatient opioid prescription fills. We conducted GWAS for each major ancestral group in MVP: African Americans (AAs; N=88,498), European Americans (EAs; N=302,585), and Hispanic Americans (HAs; N=34,861), followed by a cross-ancestry meta-analysis. Ten loci were GWS in the cross-ancestry meta-analysis, 8 of them novel. In addition to the known coding variant rs1799971 in OPRM1, which was the lead SNP genome-wide (p=6.78x10-10), and a recently reported exonic variant in FURIN, we identified intronic variants in RABEPK, FBXW4, NCAM1, and KCNN1. Ancestry-specific analyses identified an additional novel locus for each of the 3 ancestry groups. A supplementary meta-analysis within EAs that included MVP and other samples identified a locus in TSNARE1, which was also GWS in the cross-ancestry meta-analysis of all datasets. Gene-based association analyses identified 1 gene in AAs (CHRM2) and 3 in EAs (OPRM1, DRD2, and FTO). Significant genetic correlations (rg's) were identified for 127 traits, including positive correlations with schizophrenia, problematic alcohol use, and major depressive disorder. The most significantly enriched cell type group was the central nervous system with gene-expression enrichment identified in brain regions previously associated with substance use disorders. With a case sample 50% larger than that of the previous largest GWAS, we identified 14 loci for OUD, including 12 novel loci, some of which were ancestry specific. These findings increase our understanding of the biological pathways involved in OUD, which can inform preventive, diagnostic, and therapeutic efforts and thereby help to address the opioid epidemic.