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.
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.
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.
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.
1From the Department of Psychiatry, University of Washington School of Medicine; Center of Excellence in Substance Abuse Treatment and Education, and Mental Illness Research Educational and Clinical Center, VA Puget Sound Health Care System, Seattle, WA
2Washington Physicians Health Plan, Seattle, WA
†Correspondence: Andrew J. Saxon, VA Puget Sound Health Care System (S-116 ATC), Department of Psychiatry & Behavioral Sciences, University of Washington, School of Medicine, 1660 S. Columbian Way, Seattle, WA, 98108. Email:Andrew.Saxon@med.va.gov
Original manuscript received 7 October 2004; revised manuscript received 4 April 2005, accepted for publication 5 May 2005.
Supported by Center of Excellence in Substance Abuse Treatment and Education, and by Mental Illness Research Education and Clinical Center, VA Puget Sound Health Care System.