title: Common and specific liability to addiction: approaches to association studies of opioid addiction.
abstract: BACKGROUND
  Opioid addiction, whether to opiates such as heroin and morphine, and/or to non-medical use of opioids, is a major problem worldwide. Although drug-induced and environmental factors are essential for the liability to develop opioid addiction, the genetic background of an individual is now known also to play a substantial role.
  
  
  METHODS
  The overall goal of this article is to address the common and specific liabilities to addiction in the context of approaches to studies of one addiction, opioid addiction. Literature on identifying genetic variants that may play a role in the development of opioid addiction was reviewed.
  
  
  RESULTS
  A substantial number of genetic variants have been reported to be associated with opioid addiction. No single variant has been found in any of the reported GWAS studies with a substantial effect size on the liability to develop heroin addiction. It appears that there is a complex interaction of a large number of variants, some rare, some common, which interact with the environment and in response to specific drugs of abuse to increase the liability of developing opioid addiction.
  
  
  CONCLUSIONS
  In spite of the inherent difficulties in obtaining large well-phenotyped cohorts for genetic studies, new findings have been reported that are being used to develop testable hypotheses into the biological basis of opioid addiction.
authors.affiliation: Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, NY 10065, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Nielsen
authors.forename: Mary Jeanne
authors.initials: MJ
authors.lastname: Kreek
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use; D016739:Behavior, Addictive / Q000235:genetics*; D044127:Epigenesis, Genetic / Q000187:drug effects*; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D006801:Humans; D009293:Opioid-Related Disorders / Q000235:genetics*; D010641:Phenotype
chemical_list: D000701:Analgesics, Opioid