Chunk #24 — Identifying Specific Genes Related to AOD Dependence — Genes Encoding Proteins Involved in Neurotransmission — Genes Involved in the Endogenous Opioid System
Research on the role of the endogenous opioids in AOD dependence has centered mainly on a gene called OPRM1, which encodes one type of opioid receptor (i.e., the μ-opioid receptor), although the results so far have been equivocal. This gene contains a polymorphism resulting in a different protein product (i.e., a non-synonymous polymorphism) that in one study was found to bind one of the endogenous opioids (i.e., β-endorphin) three times as strongly as the main variant of the gene (Bond et al. 1998); other studies, however, could not confirm this finding (Befort et al. 2001; Beyer et al. 2004).
