Molecular characterization and haplotype combination of PrRP gene polymorphism and its association with production traits in Chinese native goats

The physiological effects of prolactin-releasing peptide (PrRP) are not only able to mediate prolactin secretion but also regulate food intake and energy homeostasis. Thus the PrRP gene is an important potential candidate gene for production performance in livestock. Here, we firstly explored the DNA sequence of the PrRP gene, the genomic organization and the genetic variants. The caprine PrRP gene is organized in two exons and is transcribed into an mRNA containing 297 bp of sequence coding for a protein of 98 amino acids. Its protein sequences showed substantial similarity, 97%, to its orthologs from cattle and sheep. Four sequence variants including three SNPs and a large insert mutation were identified in the study of four different goat populations consisting of 1408 healthy and unrelated individuals. Seven haplotypes involving four sequence variant sites in the caprine PrRP gene were identified and their effects on production traits were analyzed. The results revealed that haplotype 1 had the highest haplotype frequencies in the dairy populations and was highly significantly associated with body length (P < 0.01), chest circumference (P < 0.01) and milk yield (P < 0.05) in the analyzed populations, respectively. Our results provide evidence that polymorphisms in the PrRP gene are associated with production traits, and may be used for marker-assisted selection and management in goat breeding programs.