Gene polymorphisms in PROP1 associated with growth traits in sheep

The PROP paired-like homeobox 1 (PROP1) gene encodes a protein that regulates growth and development in mammals. Possessing DNA-binding and transcriptional activation abilities, PROP1 is able to control the expression of crucial anterior pituitary hormones including growth hormone, thyroid-stimulating hormone, and prolactin. The objective of this study was to identify genetic variation in ovine PROP1 in 670 New Zealand Romney sheep. Three single nucleotide polymorphisms (SNPs) were detected, two of which located in intron 1 were novel (c.109+40 T>C and c.109+207C>T), whilst the one located in exon 1 (c.45A>G) had been previously reported. These SNPs were arranged into three haplotypic variants - A₁, B₁ and C₁. At each locus, all three genotypes were observed with frequencies in accordance with the Hardy-Weinberg Equilibrium. Association analysis revealed that the variant GG, CC and CC genotypes for c.45A>G, c.109+40 T>C and c.109+207C>T respectively were significantly associated with higher lamb tailing and weaning weights, and growth rate-to-weaning. The A₁ haplotype had a positive effect on tailing weight, weaning weight and growth rate, while the B₁ haplotype impacted growth traits negatively. These findings suggest that variations in ovine PROP1 could serve as potential genetic markers for use in marker-assisted selection and the breeding for animals with superior growth traits.