sex and ethnicity, might also be crucial in understanding the pharmacogenetic effects of OPRM1 and other genes. In conclusion, while much progress has been made to elucidate the molecular, behavioral, and clinical effects of the Asn40Asp SNP on alcoholism etiology and treatment, much work remains to be performed before these findings may be translated into clinical practice. Limitations notwithstanding continued pursuit of this line of inquiry holds great promise to optimizing clinical care for patients suffering from alcoholism, as well as to further understand pathways of risk and recovery.