title: Genetics of alcohol dependence: a review of clinical studies.
abstract: OBJECTIVE
  Alcohol dependence is a common severe psychiatric disorder with a multifactorial etiology. Since the completion of the human genome project and with the increased availability of high-throughput genotyping, multiple genetic risk factors for substance-related disorders, including alcohol dependence, have been identified, but not all results could be replicated.
  
  
  METHODS
  We systematically review the clinical literature on genetic risk factors for alcohol dependence and alcohol-related phenotypes, including candidate gene-based studies, linkage studies and genome-wide association studies (GWAS).
  
  
  RESULTS
  Irrespectively of the methodology employed, the most robust findings regarding genetic risk factors for alcohol dependence concern genetic variations that affect alcohol metabolism. GWAS confirm the importance of the alcohol dehydrogenase gene cluster on chromosome 4 in the genetic risk for alcohol dependence with multiple variants that exert a small, but cumulative influence. A single variant with strong influence on individual risk is the aldehyde dehydrogenase 2 ALDHD2*2 variant common in Asian populations. Other robust associations have been found with previously uncharacterized genes like KIAA0040, and such observations can lead to the identification of thus far unknown signaling pathways. Converging evidence also points to a role of glutamatergic, dopaminergic and serotonergic neurotransmitter signaling in the risk for alcohol dependence, but effects are small, and gene-environment interactions further increase the complexity.
  
  
  CONCLUSIONS
  With few exceptions like ALDH2*2, the contribution of individual genetic variants to the risk for alcohol-related disorders is small. However, the concentration of risk variants within neurotransmitter signaling pathways may help to deepen our understanding of the underlying pathophysiology and thereby contribute to develop novel therapeutic strategies.
authors.affiliation: Department of Psychiatry, Pomeranian Medical University, Szczecin, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Samochowiec
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Samochowiec
authors.forename: Imke
authors.initials: I
authors.lastname: Puls
authors.forename: Przemyslaw
authors.initials: P
authors.lastname: Bienkowski
authors.forename: Björn H
authors.initials: BH
authors.lastname: Schott
mesh_terms: D000437:Alcoholism / Q000235:genetics* / Q000378:metabolism; D000444:Aldehyde Dehydrogenase / Q000235:genetics; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D056726:Genetic Association Studies; D008040:Genetic Linkage; D006801:Humans; D011506:Proteins / Q000235:genetics; D012307:Risk Factors
chemical_list: C570657:KIAA0040 protein, human; D011506:Proteins; C096127:ALDH2 protein, human; D000444:Aldehyde Dehydrogenase; D000071396:Aldehyde Dehydrogenase, Mitochondrial