Advances in QTL mapping in pigs

Abstract

Over the past 15 years advances in the porcine genetic linkage map and discovery of useful candidate genes have led to valuable gene and trait information being discovered. Early use of exotic breed crosses and now commercial breed crosses for quantitative trait loci (QTL) scans and candidate gene analyses have led to 110 publications which have identified 1,675 QTL. Additionally, these studies continue to identify genes associated with economically important traits such as growth rate, leanness, feed intake, meat quality, litter size, and disease resistance. A well developed QTL database called PigQTLdb is now as a valuable tool for summarizing and pinpointing in silico regions of interest to researchers. The commercial pig industry is actively incorporating these markers in marker-assisted selection along with traditional performance information to improve traits of economic performance. The long awaited sequencing efforts are also now beginning to provide sequence available for both comparative genomics and large scale single nucleotide polymorphism (SNP) association studies. While these advances are all positive, development of useful new trait families and measurement of new or underlying traits still limits future discoveries. A review of these developments is presented.

Figure 1

Front page of the Pig QTLdb (http://www.animalgenome.org/QTLdb/pig.html), showing database summaries and ways the database may be accessed.

Figure 2

Example of mammalian concordant lipogenesis QTL maps for human chromosomes 1 and 2 (HSA1 and HSA2) as references according to number of obesity/fat QTL reported in pig (purple), human (green), mouse (yellow), and cow (orange). The blue bars indicate the putative concordant fat QTL regions.