Opioids are commonly used medications for pain but have very high liability for misuse and addiction. There are also street opioids such heroin and the deadly fentanyl and carfentanil. There are relatively few treatment options for opioid use disorder (OUD) and the most common is a substitution with methadone (methadone maintenance treatment, MMT), a synthetic opioid. However, MMT outcomes vary greatly, with the average patient receiving MMT for multiple years and many continuing to use opioids while on MMT. There is preliminary evidence that differences in MMT response are partially determined by the individual genetic makeup. Identifying how genes affect the response to methadone has the potential to substantially improve the opioid addiction treatment outcomes via a precision medicine approach. Dr. Palmer and the BGA-LAB will collaborate with PIs Drs. James Mackillop & Zena Samaan to leverage innovations in genomic approaches to systematically examine individual variation in MMT response.