A second-generation genetic linkage map of the domestic dog, Canis familiaris

Purebred strains, pronounced phenotypic variation, and a high incidence of heritable disease make the domestic dog uniquely suited to complement genet ic analyses in humans and mice. A comprehensive genetic linkage map would a fford many opportunities in dogs, ranging from the positional cloning of di sease genes to the dissection of quantitative differences in size, shape, a nd behavior. Here we report a canine linkage map with the number of mapped loci expanded to 276 and 10-cM coverage extended to 75-90% of the genome. M ost of the 38 canine autosomes are likely represented in the collection of 39 autosomal linkage groups. Eight markers were sufficiently informative to detect linkage at distances of 10-13 cM, yet remained unlinked to any othe r marker. Taken together, the results suggested a genome size of about 27 M . As in other species, the genetic length varied between sexes, with the fe male autosomal distance being similar to 1.4-fold greater than that of male meioses. Fifteen markers anchored well-described genes on the map, thereby serving as landmarks for comparative mapping in dogs. We discuss the utili ty of the current map and outline steps necessary for future map improvemen t.