Abstract
Objective: The completion of the human genome sequence has spurred investigation of the genetic contribution to substance dependence. In this article some of the recent scientific evidence for genetic determinants of opioid and cocaine dependence is reviewed. Method: An electronic search of the medical literature was conducted to locate published studies relevant to the genetics of opioid and cocaine dependence. The collected information judged to be most pertinent is described and discussed. Results: Genetic epidemiologic studies support a high degree of heritable vulnerability for both opioid and cocaine dependence. Polymorphisms in the genes coding for dopamine receptors and transporter, opioid receptors, endogenous opioid peptides, cannabinoid receptors, and serotonin receptors and transporter all appear to be associated with the phenotypic expression of this vulnerability once opioids or cocaine are consumed. Conclusions: Despite this initial progress, identification of specific genes and quantification of associated risk for the expression of each gene remain to be elucidated. While alteration of an individual's genome to change the phenotype seems remote, future interventions for treatment of opioid and cocaine dependence may include precise medications targeted to block the effects of proteins that have been identified through genetic research.