title: Dopamine D4 receptor VNTR polymorphism associated with greater risk for substance abuse among adolescents with disruptive behavior disorders: Preliminary results.
abstract: OBJECTIVE
  The variable number tandem repeats (VNTR) polymorphism of the dopamine D4 receptor gene (DRD4) has received considerable attention as a potential genetic contributor to addiction. However, is unclear whether the polymorphism is involved in developing general traits that lead to risky behavior or an intermediate phenotype more specific to substance use disorders. Association studies have produced equivocal results. To control for potential confounds, the present study examined whether the long variant of the DRD4 VNTR polymorphism (DRD4L) is associated with greater substance misuse in a homogenous clinical sample of youth with a disruptive behavior disorder (DBD).
  
  
  METHODS
  Fifty-one psychiatrically hospitalized adolescents (mean age = 14.86 years) with a DBD diagnosis were recruited as part of a larger study. Participants provided saliva samples for genotyping procedures after completing a diagnostic interview and an assessment battery.
  
  
  RESULTS
  The odds of a substance use disorder diagnosis were significantly greater among DRD4L than DRD4S carriers (OR = 5.20, 95%CI:1.42-19.04, p = .01). Relative to DRD4S homozygotes, DRD4L carriers also reported greater marijuana use (t = -2.68, p = .01) and hard drug use (t = -2.26, p = .03).
  
  
  CONCLUSIONS
  Although adolescents with DBDs are already at heightened risk for substance misuse, the present findings suggest that DRD4L further increases those odds.
  
  
  CONCLUSIONS
  As differences persisted even among a psychiatrically homogenous sample of impulsive and risk-prone adolescents, the present findings suggest that DRD4L may be involved in the development of an intermediate phenotype specific to substance abuse (eg, cue-elicited craving).
authors.affiliation: Department of Psychology, University of Texas at Austin, Austin, Texas.|Department of Psychology, George Mason University, Fairfax, Virginia.
authors.forename: Travis T
authors.initials: TT
authors.lastname: Mallard
authors.affiliation: Department of Psychology, George Mason University, Fairfax, Virginia.
authors.forename: James
authors.initials: J
authors.lastname: Doorley
authors.affiliation: Department of Psychology, George Mason University, Fairfax, Virginia.
authors.forename: Christianne L
authors.initials: CL
authors.lastname: Esposito-Smythers
authors.affiliation: Providence VA Medical Center, Brown University Medical School, Providence, Rhode Island.|Alpert Medical School of Brown University, Brown University Medical School, Providence, Rhode Island.
authors.forename: John E
authors.initials: JE
authors.lastname: McGeary
mesh_terms: D000293:Adolescent; D019958:Attention Deficit and Disruptive Behavior Disorders / Q000150:complications* / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D050638:Receptors, Dopamine D4 / Q000235:genetics*; D019966:Substance-Related Disorders / Q000150:complications* / Q000235:genetics*
chemical_list: D050638:Receptors, Dopamine D4