Chunk #26 — Identifying Specific Genes Related to AOD Dependence — Genes Encoding Proteins Involved in Neurotransmission — Genes Involved in the Endogenous Opioid System
Researchers also have investigated genetic variations in other opioid receptors and other components of the endogenous opioid system; however, the results have been mixed. One study (Zhang et al. 2007) found modest support that the genes OPRK1 and OPRD1—which encode the κ and δ-opioid receptors, respectively—are associated with some aspects of drug dependence. Other researchers (Xuei et al. 2007) reported evidence that the genes PDYN, PENK, and POMC—which encode small molecules (i.e., peptides) that also bind to opioid receptors—may be associated with various aspects of drug dependence.
