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New Polymorphic Changes in the Wnt7A Gene and Their Effect on Reproductive Traits in Pigs

Mucha, Aurelia, Piórkowska, Katarzyna, Ropka-Molik, Katarzyna, Szyndler-Nędza, Magdalena
Annals of animal science 2018 v.18 no.2 pp. 375-385
Large White, embryo implantation, endometrium, exons, farrowing, genetic markers, genotype, humans, introns, landraces, loci, mutation, piglets, pregnancy, rearing, reproductive traits, sows, statistical analysis
For many years, research has been undertaken to identify genetic markers associated with reproductive traits in pigs, but these issues are still open to research. WNT7A expression was found in endometrium during embryo implantation as well as in early pregnancy in humans and in different species of animals. Our study was designed to identify polymorphic changes in the WNT7A gene and their effect on reproductive traits in 480 Polish Large White (PLW) and Polish Landrace (PL) pigs in 4 successive litters. As a result, 3 mutations were identified: two transitions in exon 3 g.6270G>A (rs326274214) and in intron 4 g.36251G>A (rs321204163) and deletion/insertion in intron 4 g.36220delinsAT (rs338143418). Frequency analysis of the genotypes of these polymorphisms in the WNT7A gene showed departure from Hardy-Weinberg equilibrium for PLW at locus g.36220delinsAT and for total breeds and PLW at locus g.36251G>A. Generally, the largest litters were found in sows with AA genotypes for mutations g.6270G>A and g.36251G>A and in sows with ins/ins genotype for mutation g.3622delinsAT . However, the sows of these genotypes formed only a small percentage (from 9% to 13%) in the studied group of animals. Statistical analysis showed significant differences only for the number of piglets born and reared in parity 1 (1NBA and 1N21d) in favor of the sows with genotype AA g.6270G>A (P≤0.05) and for the number of piglets born in litter 4 (4NBA) with genotype ins/ins g.3622delinsAT (P≤0.05). The analysed mutations had no effect on the age at first farrowing and the successive farrowing intervals.