title: Association of polymorphisms in the dopamine D4 receptor gene and the activity-impulsivity endophenotype in dogs.
abstract: 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.
authors.affiliation: Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Puskin u. 9, Budapest, H-1088, Hungary.
authors.forename: K
authors.initials: K
authors.lastname: Hejjas
authors.forename: J
authors.initials: J
authors.lastname: Vas
authors.forename: J
authors.initials: J
authors.lastname: Topal
authors.forename: E
authors.initials: E
authors.lastname: Szantai
authors.forename: Z
authors.initials: Z
authors.lastname: Ronai
authors.forename: A
authors.initials: A
authors.lastname: Szekely
authors.forename: E
authors.initials: E
authors.lastname: Kubinyi
authors.forename: Z
authors.initials: Z
authors.lastname: Horvath
authors.forename: M
authors.initials: M
authors.lastname: Sasvari-Szekely
authors.forename: A
authors.initials: A
authors.lastname: Miklosi
mesh_terms: D000374:Aggression; D000818:Animals; D001522:Behavior, Animal; D004285:Dogs / Q000235:genetics* / Q000502:physiology; D005787:Gene Frequency; D005838:Genotype; D007175:Impulsive Behavior / Q000235:genetics*; D010641:Phenotype; D011110:Polymorphism, Genetic; D050638:Receptors, Dopamine D4 / Q000235:genetics*
chemical_list: D050638:Receptors, Dopamine D4