Polymorphisms of the androgen receptor gene associate with fatness, uterus and ovary measurements in the pig

Abstract. Quantitative trait loci, QTL, for fatness and carcass traits in pigs have been recently mapped to the X chromosome approximately at the position where the androgen receptor gene (AR) is localized. The AR acts as a nuclear transcription factor regulating expression of a number of androgenic response genes during various stages of sexual development. The present study aimed to analyze association of the AR genotype on traits related to fatness and phenotype of primary female sexual organs, ovary and uterus. Animals of a F2 resource population based on Duroc and Berlin Miniature pig were genotyped at a multi-allelic microsatellite marker (CCTTT)n situated in the 5' untranslated region and a bi-allelic CAG-insertion/deletion polymorphism (CAG-INDEL) within exon 1 of the AR. Association analysis showed that the AR genotype both at the CAG-INDEL and microsatellite affect almost all fatness traits measured. The D allele inherited from Duroc was associated with the decrease of fat thickness. The AR genotypes also affect uterus and ovary measurements. The pigs homozygous for D allele were likely to have a lighter uterus, shorter uterus horns, oviducts and smaller ovaries than pigs homozygous for the M allele. Our results confirm the previously reported QTL for fatness traits and provide evidence for a QTL affecting dimensions of uterus and ovary on the X chromosome. The AR is a positional functional candidate gene for both trait complexes.