SC1/ECM2 maps in the central region of mouse chromosome 5. SC1/ECM2 was placed on mouse chromosome 5 by interspecific backcross analysis. The segregation patterns of SC1/ECM2 and flanking genes in 94 backcross animals that were typed for all loci are shown at the top of the figure. For individual pairs of loci, more than 94 animals were typed (see text). Each column represents the chromosome identified in the backcross progeny that was inherited from the (C57BL/6J × M spretus ) F1 parent. The 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 5 linkage map showing the location of SC1/ECM2 in relation to linked genes in shown at the bottom of the figure. Recombination distances between loci in centiMorgans are shown to the left of the chromosome, and the position 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).