Molecular and functional mapping of the piebald deletion complex on mouse chromosome 14

The piebald deletion complex is a set of overlapping chromosomal deficienci es surrounding the endothelin receptor B locus collected during the Oak Rid ge specific-locus-test mutagenesis screen. These chromosomal deletions repr esent an important resource for genetic studies to dissect the functional c ontent of a genomic region, and several developmental defects hale been ass ociated with mice homozygous for distinct piebald deletion alleles. We have used molecular markers to order the breakpoints for 20 deletion alleles th at span a 15.7-18-cM region of distal mouse chromosome 14. Large deletions covering as much as 11 chi have been identified that will be useful for reg ionally directed mutagenesis screens to reveal recessive mutations that dis rupt development. Deletions identified as haring breakpoints positioned wit hin previously described critical regions have been used in complementation studies to further define the functional intervals associated with the dev elopmental defects. This has focused our efforts to isolate genes required for newborn respiration and survival skeletal patterning and morphogenesis, and central nervous system development.