Pipelines for meta-analyses, functional SNP annotations and interaction analyses. Meta-analyses of candidate gene association studies and GWAS were illustrated in detail in STEP 1. In total, 843 vulnerable haplotypes were identified, linked by 12 risk variants and 842 vulnerable SNPs. All data and knowledge were imported to an updated version of the knowledgebase for addiction-related genes (KARG 2.0, marked with a blue box). Haplotypes identified in STEP 1 were annotated with functional and regulatory elements (STEP 2). Interaction enrichment analyses between the susceptibility genes and addiction-regulated genes previously identified by molecular biology studies (KARG 1.0, marked with a blue box) were performed (STEP 3).