The sequence includes 6.2 million sequence reads that span approximately 78% of the genome. The above mapping efforts are complemented by the recent release of a 1.5x sequence of a Standard Poodle genome. A well-defined synteny between the dog and human genomes was established as a function of this work and from extensive reciprocal chromosome painting studies. The map also defines a minimal screening set of 325 highly informative well-spaced markers, to be used in the initiation of genome-wide scans. The map was constructed using the RHDF5000-2 whole genome radiation hybrid panel and features markers mapped to 3009 unique positions, defining an average inter-marker distance of one megabase (Mb). The most recently published RH map of the dog comprises 3270 markers including 1596 microsatellite-based markers, 900 canine-specific cloned gene sequences and expressed sequence tags (ESTs), and an initial set of 668 canine-specific BAC-ends. Three major advances in the development of resources for mapping canine disease genes have been: 1) the development of a radiation hybrid (RH) map composed of large numbers of microsatellite markers and genes that link the canine and human genomes, 2) the development of canine specific whole chromosome paints that have allowed preliminary assignment of conserved segments between human and dog and 3) the publication of a 1.5x genome sequence of the dog. These results provide a necessary resource for the canine genome mapping community to undertake positional cloning experiments and provide new insights into the comparative canine-human genome maps. For 2233 markers, the orthologous human genes have been established, allowing the identification of 79 conserved segments (CS) between the dog and human genomes, dramatically extending the length of most previously described CS. Excluding the Y chromosome, the map features an RH/FISH mapped BAC every 3.5 Mb and an RH mapped BAC-end, on average, every 2 Mb. The two data sets show excellent concordance. The radiation hybrid (RH) map features a density of one marker every 900 Kb and contains 1760 bacterial artificial chromosome clones (BACs) localized to 1423 unique positions, 851 of which have also been mapped by fluorescence in situ hybridization (FISH). The resulting resource encompasses 4249 markers, and was constructed using the RHDF5000-2 whole genome radiation hybrid panel. To facilitate both genetic mapping and cloning efforts, we have constructed an integrated canine genome map that is both dense and accurate.
Understanding the genetic basis of both phenotypic variation and disease susceptibility in the dog provides new ways in which to dissect the genetics of human health and biology. Each breed features a defining constellation of morphological and behavioral traits, often generated by deliberate crossing of closely related individuals, leading to a high rate of genetic disease in many breeds. The 156 breeds of dog recognized by the American Kennel Club offer a unique opportunity to map genes important in genetic variation.
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