A confirmed association between DNA variants in CAPN9, OSM, and ITGAM candidate genes and the risk of umbilical hernia in pigs

Umbilical hernia (UH) is one of the most prevalent defects of swine, affecting their welfare and causing considerable economic loss. The molecular mechanisms behind UH in pigs remain poorly understood. The aim of this study was to verify the association between UH and previously reported DNA variants in the CAPN9, OSM, ITGAM, and NUGGC genes. A case/control study design was applied in two different crossbred cohorts of commercial fatteners containing 412 and 171 pigs, respectively. SNPs within CAPN9, OSM, and ITGAM were analyzed using Sanger sequencing, and 10 SNPs in CAPN9, five in OSM, and two in ITGAM were identified. A structural variant in the NUGGC gene was studied by droplet-digital PCR, and an elevated copy number was detected in only a single individual. Significant differences in allele frequencies for four SNPs in CAPN9 were detected. The haplotype analysis showed the effect on the risk of UH for two genes. The CAGGA haplotype within OSM and AT haplotype in ITGAM reduced the relative risk of UH by 52% and 45%, respectively, confirming that variants in those genes are associated with the risk of UH in pigs. Moreover, the interaction between the CAPN9 haplotype and the sex of animals had also significant impact on UH risk.