Chromosome Location and Association of Haplotypes of Insulin-like Growth Factor Binding Protein-2 with Production Performance in Swine

Insulin-like growth factor binding protein-2 is a member of the insulin-like growth factor families. Using a porcine RH panel, the gene was mapped on chromosome 15q22-23. Meanwhile, using polymerase chain reaction single strand conformation polymorphism, genotypic and allelic frequencies were analyzed in 17 pig breeds (total animals 570), together with a chi-square test of Hardy–Weinberg equilibrium. Also the association between haplotypes and production performance was analyzed in a Lantang × Landrace population family ( n = 133, total 43 traits). At each locus we investigated, all the breeds showed different genotypic and allelic frequency distributions. In general, the Chinese native pig breeds carried a higher allele A frequency (over 50%) than the European pigs. For production performance, pigs with the CAG haplotype had higher fore-body and rear-body weight than those with the TGT and TAG haplotypes ( P < 0.05). Also, pigs with the CAG haplotype had higher bone weight of the rear-body than those with the CAT haplotype ( P < 0.05); pigs with the TGT and CAG haplotypes had higher forelimb and rearlimb weight than those with the CAT haplotype ( P < 0.01 and P < 0.05, respectively); pigs with the TGG haplotype had higher leaf fat weight than those with the TGT and CAG haplotypes ( P < 0.05); and pigs with the CAG haplotype had more stomach weight than those with the CAT and CGT haplotypes ( P < 0.01); pigs with the TGT and CAG haplotypes had more ribs and longer body than those with the CGT–TGG, and CAT–TAG haplotypes ( P < 0.05). These results suggest that IGFBP-2 is associated with production performance, but our population family was small. More studies with large samples are needed before the IGFBP-2 locus will be useful for a selection program.