OPRM1 and psychiatric disorder: Taken together, the individual GWAS results and various approaches to assessing the genetics shared between opioid addiction and other phenotypes, the current studies suggest that the strongest variant-level associations (e.g., those in OPRM1 and FURIN) may be specific to opioid addiction, while weaker signals (e.g., in and around RABEPK) may be shared with other SUDs and psychiatric disorders.