Association analysis of exon III and exon I polymorphisms of the dopamine D4 receptor locus in Mexican psychotic patients

Psychiatry Res. 2007 Dec 3;153(3):209-15. doi: 10.1016/j.psychres.2006.12.011. Epub 2007 Sep 5.


In this study, we investigated whether polymorphisms of the dopamine D4 receptor (DRD4) gene were associated with psychotic symptomatology rather than with a unique diagnosis such as schizophrenia. A number of association studies between the DRD4 gene 48 bp-VNTR polymorphism at exon 3 and psychotic disorders have been reported, but the results have been controversial. Both 48 bp-VNTR and the 12 bp-VNTR (at exon 1) polymorphisms of this gene were analyzed in a group of 149 unrelated Mexican subjects with a diagnosis of schizophrenia, schizoaffective disorder, schizophreniform disorder, major depression and bipolar disorder, both with psychotic symptoms, brief psychotic disorder, delusional disorder and non-specific psychotic disorder, and in 169 individuals free of psychiatric illnesses. There were no differences in allele or genotype frequencies between groups for the 12 bp-VNTR polymorphisms. However, a significant excess of "rare" alleles (3-, 5-, 6- and 8-48 bp repeats alleles) was found in the group of psychotics. Moreover, haplotypes 3-A1, 5-A1, 6-A1 and 8-A1 were significantly more frequently associated with cases. This positive association supports a role of this molecule as a genetic risk factor in psychotic disorders.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Bipolar Disorder / diagnosis
  • Bipolar Disorder / genetics
  • Depressive Disorder, Major / diagnosis
  • Depressive Disorder, Major / genetics
  • Ethnic Groups / genetics*
  • Exons / genetics*
  • Female
  • Gene Frequency
  • Genetic Predisposition to Disease
  • Genotype
  • Haplotypes
  • Humans
  • Male
  • Mexico / ethnology
  • Middle Aged
  • Minisatellite Repeats / genetics*
  • Polymorphism, Genetic / genetics*
  • Psychotic Disorders / diagnosis
  • Psychotic Disorders / genetics*
  • Receptors, Dopamine D4 / genetics
  • Risk Factors
  • Schizophrenia, Paranoid / diagnosis
  • Schizophrenia, Paranoid / genetics


  • Receptors, Dopamine D4