title: Elevated levels of DNA methylation at the OPRM1 promoter in blood and sperm from male opioid addicts.
abstract: OBJECTIVE
  The OPRM1 gene was studied for DNA methylation in opioid dependence and possible paternal contribution to epigenetic inheritance of altered methylation profiles.
  
  
  METHODS
  DNA was extracted from blood and sperm from 13 male opioid addicts and 21 male control subjects. DNA methylation was determined by pyrosequencing in 24 CpG sites at the OPRM1 promoter region.
  
  
  RESULTS
  The authors found significantly increased overall methylation in blood DNA from addicted subjects (Kruskal-Wallis [K-W] p = 0.013). Seven CpG sites showed significantly hypermethylated blood DNA from cases when compared with blood DNA from controls (p < 0.05 at CpGs 5, 9, 10, 11, 18, 23, and 24). In sperm-derived DNA from addicts, the methylation was significantly increased at CpG 2 (p = 0.012), and overall methylation did not reach significant difference (K-W p = 0.523).
  
  
  CONCLUSIONS
  Increased DNA methylation in the OPRM1 gene is associated with opioid dependence. Hypermethylated CpG sites located in OPRM1 promoter may potentially block the binding of Sp1 and other transcription activators, thus leading to OPRM1 silencing. The increased DNA methylation in sperm may suggest a way of epigenetic heritability of opioid abuse or dependence phenotypes.
authors.affiliation: Department of Psychiatry, Washington University School of Medicine, Saint Louis, Missouti, USA.
authors.forename: Vesselin M
authors.initials: VM
authors.lastname: Chorbov
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Todorov
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lynskey
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Cicero
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D018899:CpG Islands; D019175:DNA Methylation; D016002:Discriminant Analysis; D020022:Genetic Predisposition to Disease; D040941:Heredity; D006556:Heroin Dependence / Q000097:blood / Q000235:genetics; D006801:Humans; D008297:Male; D008923:Missouri; D009293:Opioid-Related Disorders / Q000097:blood / Q000235:genetics*; D010375:Pedigree; D011401:Promoter Regions, Genetic; D017450:Receptors, Opioid, mu / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013094:Spermatozoa / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C485764:OPRM1 protein, human; D017450:Receptors, Opioid, mu