Allelic variation of two poly-glutamine repeats in the canine androgen receptor gene

Abstract

Various dog breeds can differ markedly not only in size and shape but also in behavioral traits, suggesting that some behavioral traits are under genetic control. In humans, reports indicate that personality can be affected by genetic polymorphisms of proteins involved in regulation of neurotransmitters such as dopamine and serotonin and hormones such as androgen and estrogen. In the previous studies, we found that the longer alleles of a VNTR in exon III of the dopamine receptor D4 gene might affect aggressiveness in dogs. However, the number of genes surveyed is not enough and genetic systems affecting canine behavior are still unknown. In the present study, we surveyed 2 polymorphic glutamine repeat regions of the canine androgen receptor gene (AR) in 30 dog breeds (720 individuals) and 2 wolf subspecies (30 individuals). In the first repeat (Q1), we detected 3 alleles, Q1-10, Q1-11 and Q1-12, each includes 10, 11 and 12 deduced poly-glutamines, respectively. In the second repeat (Q2), 6 alleles, Q2-22, Q2-23, Q2-24, Q2-25, Q2-26 and Q2-27, including two new alleles (Q2-26 and Q2-27) were detected. Allele frequencies differed greatly among breeds/subspecies. These polymorphisms in AR may be useful markers for further analysis of the association of genes with reproductive traits and behavioral ones.