The opioid system in alcohol and drug dependence: family-based association study.
Opioid receptors and their endogenous peptide ligands play important roles in neurotransmission and neuromodulation in response to addictive drugs such as heroin, cocaine, and alcohol. In an earlier study, we reported that variation in the genes encoding the kappa-opioid receptor (OPRK1) and its peptide ligand (PDYN) were associated with the risk for alcoholism. We continued our investigation of the role of the opioid system in alcohol dependence by analyzing the genes encoding the micro- and delta-opioid receptors and their peptide ligands. We analyzed 18 OPRM1 SNPs, 18 OPRD1 SNPs, 7 PENK SNPs, and 7 POMC SNPs in a sample of 1923 European Americans from 219 multiplex alcohol dependent families. Employing a family-based test of association, we found no evidence that these four genes were significantly associated with alcohol dependence. We also did not find association between these genes and illicit drug dependence. Secondary analyses employing the narrower phenotype of opioid dependence (83 affected individuals) demonstrated association with SNPs in PENK and POMC, but not in OPRM1 or OPRD1. Haplotype analyses provided further support for the association of PENK and POMC with opioid dependence. Therefore, our data provide no support for the idea that variations in OPRM1, OPRD1, PENK and POMC are associated with alcohol dependence or general illicit drug dependence, but variations in PENK and POMC appear to be associated with the narrower phenotype of opioid dependence in these families.
Xuei
Xiaoling
X
Indiana University School of Medicine, 1345 W 16th Street, Indianapolis, IN 46202, USA. xxuei@iupui.edu
Flury-Wetherill
Leah
L
Bierut
Laura
L
Dick
Danielle
D
Nurnberger
John
J
Foroud
Tatiana
T
Edenberg
Howard J
HJ
D000437:Alcoholism / Q000235:genetics*; D005190:Family; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D018847:Opioid Peptides / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011957:Receptors, Opioid / Q000235:genetics*; D017465:Receptors, Opioid, delta / Q000235:genetics; D017450:Receptors, Opioid, mu / Q000235:genetics
C485764:OPRM1 protein, human; D018847:Opioid Peptides; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu