Linkage Analysis.

<p>(A) Based on the phenotype, a targeted approach was used to establish linkage to <i>Fras1</i> in the <i>bfb</i> strain. Polymorphic markers flanking the four previously characterised <i>blebs</i> genes (open boxes) were used to identify a candidate for sequencing. Strong linkage was observed with the <i>Fras1</i> gene (grey box). (B) A genome-wide scan established linkage to chromosome 17 in the <i>cauli</i> strain. Chromosome 17-specific markers were then used to refine linkage to a 7 Mb region between rs3667809 and rs3684506 (grey boxed region) containing 218 genes. No additional informative markers were available to further refine the linkage region. (C) A genome-wide scan established linkage to chromosome 7 in the 12BCC-22a line. Subsequent analysis using chromosome 7-specific markers refined linkage to a 32 Mb region containing approximately 700 genes. Numbers to the left in each diagram denote individual mutant embryos except in (C) where both mutant and unaffected embryos are shown. Black boxes denote homozygous C57BL/6 alleles, grey boxes denote C57BL6/C3H heterozygosity, white boxes denote untested markers.