MAOA-uVNTR polymorphism in a Brazilian sample: further support for the association with impulsive behaviors and alcohol dependence

Am J Med Genet B Neuropsychiatr Genet. 2006 Apr 5;141B(3):305-8. doi: 10.1002/ajmg.b.30290.


The enzyme monoamine oxidase A (MAO A) plays an important role in the metabolism of neurotransmitters. The MAOA gene presents several polymorphisms, including a 30-bp VNTR in the promoter region (MAOA-uVNTR). Alleles with 3.5 and 4 repeats are 2-10 times more efficient than the 3-repeat allele. Several studies have shown an association between the 3-repeat allele and a cluster of externalizing behaviors including alcoholism, antisocial personality, and impulsivity. The objective of the present study is to replicate in a different culture the associations between the MAOA-uVNTR with alcoholism and other phenotypes. The sample comprises 125 Brazilian alcoholics of European descent and 235 controls. The results suggest that the 3-repeat allele is associated to: (1) alcohol dependence (P < 0.05); (2) an earlier onset of alcoholism (P < 0.01); (3) comorbid drug abuse among alcoholics (P < 0.05); and (4) a higher number of antisocial symptoms (P < 0.02). Our results confirmed previous reports showing an association of the low activity 3-repeat allele of MAOA-uVNTR polymorphism with substance dependence and impulsive/antisocial behaviors. These findings in a different culture further support the influence of the MAOA-uVNTR in psychiatric disorders.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcoholism / genetics
  • Alcoholism / psychology
  • Alleles
  • Analysis of Variance
  • Brazil
  • Gene Frequency
  • Genotype
  • Humans
  • Impulsive Behavior / genetics
  • Impulsive Behavior / psychology
  • Male
  • Minisatellite Repeats / genetics*
  • Monoamine Oxidase / genetics*
  • Polymorphism, Genetic*
  • Promoter Regions, Genetic / genetics*


  • Monoamine Oxidase