Combined homozygosity analysis. An ideogram of bovine chromosome 4 (BTA4; adapted from http://www.marc.usda.gov/genome/htmls/LinkageMap.jsp?Species=bos&Chromosome=4) is displayed alongside an enlargement of the extended regions of homozygosity detected in each of eight affected calves. Individual homozygous segments are depicted as gray rectangles, and the chromosomal positions (in Mb) of each bounding marker are indicated at the top and bottom of each segment. The homozygous segment on the far right represents one animal that was only genotyped for microsatellite markers between 107.14 Mb and 123.48 Mb; therefore, the extent of homozygosity proximal to 107.14 Mb is unknown, as indicated by the question mark. The overall region of homozygosity, from 90.65 Mb to 124.13 Mb, is bounded by dashed lines. The consensus region of homozygosity shared by all affected calves, from 115.61 Mb to 119.00 Mb, is bounded by solid black lines. Thus, the osteopetrosis disease locus has been mapped to this 3.4-Mb region. The overall figure has been adapted from .