Chunk #25 — Identifying Specific Genes Related to AOD Dependence — Genes Encoding Proteins Involved in Neurotransmission — Genes Involved in the Endogenous Opioid System
Laboratory studies have suggested that OPRM1 is associated with sensitivity to the effects of alcohol (Ray and Hutchison 2004). In addition, several studies have reported evidence of an association between OPRM1 and drug dependence (e.g., Bart et al. 2005). Other studies, however, have failed to find such an association (e.g., Bergen et al. 1997), and a combined analysis of several studies (i.e., a meta-analysis) concluded that no association exists between the most commonly studied OPRM1 polymorphism and drug dependence (Arias et al. 2006). However, this finding does not preclude the possibility that other genetic variants in OPRM1 and/or other genes related to the endogenous opioid system are involved in risk for drug dependence. For example, a recent study determining the genotypes of multiple genetic variants across the gene uncovered evidence of association with OPRM1 and AOD dependence (Zhang et al. 2006).
