Allele-specific expression and high-throughput reporter assay reveal functional genetic variants associated with alcohol use disorders

• Published in: Molecular psychiatry 2021-04, Vol.26 (4), p.1142-1151
• Main Authors: Rao, Xi, Thapa, Kriti S., Chen, Andy B., Lin, Hai, Gao, Hongyu, Reiter, Jill L., Hargreaves, Katherine A., Ipe, Joseph, Lai, Dongbing, Xuei, Xiaoling, Wang, Yue, Gu, Hongmei, Kapoor, Manav, Farris, Sean P., Tischfield, Jay, Foroud, Tatiana, Goate, Alison M., Skaar, Todd C., Mayfield, R. Dayne, Edenberg, Howard J., Liu, Yunlong
• Format: Article
• Language: English
• Subjects: 13/106; 13/109; 3' Untranslated regions; 3' Untranslated Regions - genetics; 38; 38/23; 38/47; 38/90; 38/91; 631/208; 631/378; Alcohol use; Alcoholics; Alcoholism; Alcoholism - genetics; Alleles; Behavioral Sciences; Binding sites; Biological Psychology; Cell lines; Computational neuroscience; Gene expression; Genetic aspects; Genetic diversity; Genetic Predisposition to Disease - genetics; Genome-wide association studies; Genome-Wide Association Study; Genomes; Health aspects; Heterozygotes; Humans; Identification and classification; Linkage disequilibrium; Medicine; Medicine & Public Health; miRNA; Neurosciences; Non-coding RNA; Pharmacotherapy; Polymorphism, Single Nucleotide - genetics; Psychiatry; Ribonucleic acid; Risk factors; RNA; RNA-binding protein; Single nucleotide polymorphisms; Single-nucleotide polymorphism; Transcriptomes
• ISSN: 1359-4184; 1476-5578
• DOI: 10.1038/s41380-019-0508-z

Genome-wide association studies (GWAS) of complex traits, such as alcohol use disorders (AUD), usually identify variants in non-coding regions and cannot by themselves distinguish whether the associated variants are functional or in linkage disequilibrium with the functional variants. Transcriptome studies can identify genes whose expression differs between alcoholics and controls. To test which variants associated with AUD may cause expression differences, we integrated data from deep RNA-seq and GWAS of four postmortem brain regions from 30 subjects with AUD and 30 controls to analyze allele-specific expression (ASE). We identified 88 genes with differential ASE in subjects with AUD compared to controls. Next, to test one potential mechanism contributing to the differential ASE, we analyzed single nucleotide polymorphisms (SNPs) in the 3′ untranslated regions (3′UTR) of these genes. Of the 88 genes with differential ASE, 61 genes contained 437 SNPs in the 3′UTR with at least one heterozygote among the subjects studied. Using a modified PASSPORT-seq (parallel assessment of polymorphisms in miRNA target-sites by sequencing) assay, we identified 25 SNPs that affected RNA levels in a consistent manner in two neuroblastoma cell lines, SH-SY5Y and SK-N-BE(2). Many of these SNPs are in binding sites of miRNAs and RNA-binding proteins, indicating that these SNPs are likely causal variants of AUD-associated differential ASE. In sum, we demonstrate that a combination of computational and experimental approaches provides a powerful strategy to uncover functionally relevant variants associated with the risk for AUD.