[Inheritance and disease in the pig: possibilities of use for breeding]

Single-locus disorders in domesticated animals were among the first Mendelian traits to be documented, and to be included in early linkage maps. The use of linkage maps and comparative genomics has been essential to the identification of the causative genes for disorders. A DNA marker for selection of resistance to F18+ E. coli in the pig is available since several years. The use of this marker decreases mortality due to post-weaning diarrhoea and/or oedema disease. For more than 100 disorders the molecular lesion has been identified and hence for which a DNA test is available. However, for most diseases such as Porcine Reproductive and Respiratory Syndrome (PRRS) and Porcine Circovirus Associated Diseases (PCVAD), resistance is a complex and polygenic trait. Novel technologies such as gene microarrays and advanced bioinformatics are being used to analyse health data. Lagging behind, however, is availability of large DNA data sets from pedigreed populations with accurately measured health phenotypes that are needed to identify associations between markers and health traits. As the pig genome is sequenced to a great extent and ten thousands of markers can be analysed at a reasonable price, genomic selection for health traits is possible.