SNPs that were significantly associated with alcohol consumption (P<5 × 10−8) in the GWAS were assessed to determine whether they were potential expression quantitative trait loci (eQTLs) using the Genotype Tissue Expression Portal (GTEx) (http://www.gtexportal.org). GTEx uses gene expression data from multiple human tissues linked to genotype data to provide information on eQTLs. Gene-based analyses were performed using MAGMA,39 derived from SNP summary data from the GWAS of alcohol consumption in this sample. The 1000 genomes European reference panel (phase 1, release 3) was used to account for LD in the sample. SNPs were mapped to genes using the NCBI 37.3 gene locations and Entrez gene IDs. This resulted in 18 024 genes available for analysis that, after Bonferroni correction (0.05/18 024), gave a threshold for statistical significance at 2.8 × 10−6.
