title: Genetic influences on quantity of alcohol consumed by adolescents and young adults.
abstract: OBJECTIVE
  To examine genetic and environmental influences on drinking in a nationally representative study of genetically informative adolescents followed into young adulthood.
  
  
  METHODS
  The average quantity of alcohol used per drinking episode during the past year was analyzed in 4432 youth assessed during adolescence (mean age of 16) and then 1 and 6 years later. The variance of quantity of alcohol consumed was decomposed into three components: additive genetic (a2), shared environmental (c2), non-shared environmental (e2). Four candidate genes were tested for association.
  
  
  RESULTS
  Wave 1 a2-0.52e2-0.48, Wave 2 a2-0.28e2-0.72, Wave 3 a2-0.30e2-0.70. Genetic correlations between Waves 1 and 2 were 0.85, Waves 1 and 3 were 0.34. The DAT1 440 allele was associated at Wave 1 (p=0.007). DRD2 TaqI A1/A2 was associated at Wave 3 (p=0.007). DRD4 and 5HTT were not associated. The DAT1 and DRD2 polymorphisms accounted for 3.1% and 2.0% of the variation, respectively.
  
  
  CONCLUSIONS
  Genetic influence on drinking behavior was common in adolescents longitudinally assessed 1 year apart, but was less correlated between these adolescents and their assessment as young adults at a subsequent time point. Polymorphisms in genes of the dopaminergic system appear to influence variation in drinking behavior.
authors.affiliation: Department of Psychiatry, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Box C-268-35, Denver, CO 80262, USA. Christian.Hopfer@uchsc.edu
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Hopfer
authors.forename: David
authors.initials: D
authors.lastname: Timberlake
authors.forename: Brett
authors.initials: B
authors.lastname: Haberstick
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Lessem
authors.forename: Marissa A
authors.initials: MA
authors.lastname: Ehringer
authors.forename: Andrew
authors.initials: A
authors.lastname: Smolen
authors.forename: John K
authors.initials: JK
authors.lastname: Hewitt
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000235:genetics; D000428:Alcohol Drinking / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D017448:Receptors, Dopamine D2 / Q000235:genetics; D012931:Social Environment; D019914:Taq Polymerase / Q000235:genetics; D014427:Twins / Q000235:genetics; D014481:United States / Q000453:epidemiology
chemical_list: D017448:Receptors, Dopamine D2; D019914:Taq Polymerase