This study is the first to analyze PTHR1 and LEF1 as functional candidate genes for the inverted teat defect in pigs. Detected SNP in both genes, which are involved in the ontogenesis of a functional mammary gland, could be shown as significantly associated with the inverted teat phenotype as well as teat number in an experimental pig population. Furthermore, LEF1 exhibited association with that defect in a commercial population.
QTL analyses for inverted teats revealed significant QTL on twelve chromosomes in an experimental and five chromosomes in a commercial pig population. On SSC3, SSC4, SSC6 and SSC11 overlapping QTL in both populations could be detected and enabled the information about novel positional candidate genes.
Adjacent microarray analyses of epithelial and mesenchymal teat tissues of affected and non-affected animals offered differentially regulated genes of biological processes involved in mammary gland development. Constitutive quantitative real-time analyses of FGFR2, GHR, HGF, PDGFA, PDGFRA, PDGFB and VEGF revealed significant differential expressions in the compared animals with normal against inverted teats.