An application of the comparative mapping of genes and other genetic markers in the genomes of several mammalian species to the localization to a specific chromosomal locus of a gene, in particular one thought to be related to a genetic disease (a candidate disease gene). Because mammalian evolution has resulted in relatively few gene relocations, and since those that have occurred seem to be random, knowledge of linkages of genes in mammalian species may be helpful in locating a gene in another mammal's genome.