Osmr maps in the proximal region of mouse chromosome 15. Osmr was placed on mouse chromosome 15 by interspecific backcross analysis. The segregation patterns ofOsmr and flanking genes in 127 backcross animals that were typed for all loci are shown at the top. For individual pairs of loci, >127 animals were typed. Each column represents the chromosome identified in the backcross progeny that was inherited from the (C57BL/6J × M. spretus) F1 parent. Shaded boxes represent the presence of a C57BL/6J allele, and white boxes represent the presence of a M. spretus allele. The number of offspring inheriting each type of chromosome is listed at the bottom of each column. A partial chromosome 15 linkage map showing the location ofOsmr in relation to linked genes is shown at the bottom. Recombination distances between loci (in centimorgans) are shown to the left of the chromosome, and the positions of loci in human chromosomes, where known, are shown to the right. References for the human map positions of loci cited in this study can be obtained from GDB (Genome Data Base), a computerized database of human linkage information maintained by The William H. Welch Medical Library of The Johns Hopkins University (Baltimore, MD).