Positional cloning of genes involved in major congenital diseases in pig
Résumé
Congenital diseases are defined as a physical defect or a health problem that is present at birth. Despite a quite low incidence of these diseases (1-3%), these defects are a significant problem in the pig industry and lead to severe economic loss and poor animal welfare. The most important congenital defects that occur in piglets are urogenital, including testicular migration defects (scrotal or inguinal hernias, cryptorchidism) and gonadal differentiation anomalies (intersexuality). Beside sanitary and environmental factors, frequencies of disorders are known to be influenced by genetic components. The aim of this work, developed in the frame of the SwAn project, is the identification of genes underlining congenital hereditary disorders in pigs for further marker assisted selection against genetic defects. SwAn is a collaborative project with the French private pig breeding companies, the French pig institute (IFIP), and INRA (National Institute of Agronomic Research). A collection of 1800 samples of affected piglets, and their two non-affected parents was established with the French pig breeders. A genome-wide association study (GWAS) with a SNP panel comprising 60 000 markers (Illumina©) and covering the entire genome was performed. Results obtained for intersexuality, scroto-inguinal hernia and cryptorchidism will be presented. The overall expected impact of SwAn is to improve the sustainability of pork production as well as pig health and welfare. Moreover, identification of causative genes in pigs would be relevant for similar diseases in humans and other mammalian species.