Androgen receptor gene polymorphisms are associated with aggression in Japanese Akita Inu

Abstract

We tested for an association between variable number of tandem repeats in the canine androgen receptor (AR) gene and personality differences in Japanese Akita Inu dogs. The polymorphic trinucleotide (CAG) repeat region coding for glutamine in exon 1 of the AR gene was genotyped using genomic DNA obtained from 171 dogs. Three alleles (23, 24 and 26 repeats) were detected, and the allele frequency differed with the coat colour. We assessed the personality profiles of 100 fawn-coloured dogs (54 males and 46 females) based on a questionnaire answered by each dog's owner. The questionnaire consisted of five sub-scales (sociability, playfulness, neuroticism, aggressiveness, distractibility), and the psychometric properties were acceptable based upon internal consistency of the subscales. We found that male dogs with a short allele conferring increased AR function had higher aggressiveness scores than male dogs with longer alleles. By contrast, no evidence was found for a relationship between AR gene variants and personality in females. To our knowledge, our findings provide the first evidence of polymorphism in the AR gene being associated with canine aggression.

The Personality of Dogs

“…Devoted efforts of researchers working on dogs provided several tools for characterising individual behaviour (e.g., Sheppard & Mills, 2002;Hsu & Serpell, 2003;Mirkó et al, 2012), identified breed (genetic) differences (e.g., Wilsson & Sundgren, 1997a,b;Svartberg, 2002Svartberg, , 2006Strandberg et al, 2005;Turcsán et al, 2011), uncovered some gene polymorphisms associated with personality traits (e.g., Héjjas et al, 2007b;Takeuchi et al, 2009a,b;Konno et al, 2011), and studied the effect of development or stability of the behaviour characteristics over an extended period of time (e.g., Wilsson & Sundgren, 1998;Slabbert & Odendaal, 1999;Svobodová et al, 2008). Thus, understanding function and mechanisms of dog personality has a wide range of practical applications, including significant influence on the dog-human bond, dog welfare, and even human health.…”

“…So far, numerous genes have been mapped for morphological traits and diseases , but the identification of genes underlying behavioural phenotype is still lagging behind. However, several single nucleotide polymorphisms (SNPs), variable number of tandem repeats (VNTRs), and copy number variants of candidate genes relating to androgen, serotonin, dopamine, and other systems already have been sequenced (e.g., Héjjas et al, 2007b;van den Berg et al, 2008;Konno et al, 2011; for a review, see Hall & Wynne, 2012). Specific genes have been identified either by candidate gene approach (Héjjas et al, 2007a;Takeuchi et al, 2009a;Våge et al, 2010) or by genome-wide association studies (GWAS; Dodman et al, 2010;Tiira et al, 2012).…”

Repeat polymorphism analysis for examining genetic variability and the implications for specific traits in dog breeds

“…Analysis of polymorphic trinucleotide (CAG) repeat size (or number) in exon 1 of the AR gene indicated that male dogs with a short allele had increased AR function and showed higher aggressiveness scores than those with longer alleles (Konno et al, 2011). In vitro studies have demonstrated that the human AR gene with a relatively short CAG repeat sequence possesses enhanced transcriptional activity by promoting the interaction between the receptor and co-activator (Chamberlain et al, 1994).…”

“…Firstly, microsatellites related to behavior-related genes had a variable repeat size (or number) and affected behavioral characteristics in dog breeds (Takeuchi et al, 2009a(Takeuchi et al, , 2009bKonno et al, 2011), and could also interact with SNPs in the regulation of transcription (Chen et al, 2013). Secondly, VNTRs of the dopaminergic neurotransmitter genes such as DRD4, TH, DBH, and DAT were reviewed in dogs (Hejjas et al, 2007(Hejjas et al, , 2009, and a repeat polymorphism of the TH gene was related to behavioral tests (Kubinyi et al, 2012).…”

“…Among repeat elements that are classified based on their structure and size of repeat unit, microsatellites in mammalian genomes consist of the simplest tandem repeats of short units, which could be effective genetic markers for dog breed phylogeny, genetic variation, and quality control (Irion et al, 2003;Ellegren, 2004). An investigation of the trinucleotide (CAG) repeat encoding glutamine in exon 1 of the androgen receptor (AR) gene indicated that polymorphisms of the CAG microsatellite are associated with aggression in Japanese Akita Inu (Konno et al, 2011). A relatively short CAG repeat sequence enhances the transcriptional activity of AR by promoting the interaction between the receptor and co-activator (Chamberlain et al, 1994).…”