Association of polymorphisms in the dopamine D4 receptor gene and the activity-impulsivity endophenotype in dogs

Anim Genet. 2007 Dec;38(6):629-33. doi: 10.1111/j.1365-2052.2007.01657.x. Epub 2007 Nov 6.


A variable number of tandem repeats (VNTR) polymorphism in exon 3 of the human dopamine D4 receptor gene (DRD4) has been associated with attention deficit hyperactivity disorder (ADHD). Rodents possess no analogous repeat sequence, whereas a similar tandem repeat polymorphism of the DRD4 gene was identified in dogs, horses and chimpanzees. Here, we present a genetic association study of the DRD4 VNTR and the activity-impulsivity dimension of the recently validated dog-ADHD Rating Scale. To avoid false positives arising from population stratification, a single breed of dogs (German shepherd) was studied. Two DRD4 alleles (referred to as 2 and 3a) were detected in this breed, and genotype frequencies were in Hardy-Weinberg equilibrium. For modelling distinct environmental conditions, 'pet' and 'police' German shepherds were characterized. Police German shepherds possessing at least one 3a allele showed significantly higher scores in the activity-impulsivity dimension of the dog-ADHD Rating Scale than dogs without this allele (P = 0.0180). This difference was not significant in pet German shepherds. To the best of our knowledge, this is the first report of an association between a candidate gene and a behaviour trait in dogs, and it reinforces the functional role of DRD4 exon 3 polymorphism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aggression
  • Animals
  • Behavior, Animal*
  • Dogs / genetics*
  • Dogs / physiology
  • Gene Frequency
  • Genotype
  • Impulsive Behavior / genetics*
  • Phenotype
  • Polymorphism, Genetic*
  • Receptors, Dopamine D4 / genetics*


  • Receptors, Dopamine D4