Schematic representation of chromosome 8. Markers shown were used to genotype mice of the F2 crosses. Intermarker distances (right; in cM) are based on the frequency of recombination in the crosses: 305(BALB/cJ × BXH-2)F2 and 278(A/J × BXH-2)F2. However, their absolute positions in megabase (Mb; left) along the chromosome are based on National Center for Biotechnology Information (NCBI; www.ncbi.nlm.nih.gov/genome/guide/mouse/) and Ensembl project (www.ensembl.org) databases. The centromere is identified by a large dot.