The loci include OPRM1, OPRK1, and OPRD1, the endogenous opioid peptide PNOC, the dopamine-metabolizing enzyme catechol-O-methyltransferase (COMT), and the methadone-metabolizing enzyme CYP2B6. The majority of these associations with NAS severity were point-wise significant but failed to reach experiment-wise significance when applying multiple-testing correction. This evidence concerns the gene COMT and neonatal abstinence syndrome.