Mapping of PCR-based markers for mouse chromosome 4 on a backcross penetrant for the misty (m) mutation.

A genetic linkage map for mouse Chromosome (Chr) 4 (MMU 4) has been constructed with an intersubspecific backcross between the C57BL/KsJ strain homozygous for the misty (m) coat color locus and the inbred Mus musculus musculus Czech II strain. Several recently developed PCR-based simple sequence length polymorphism (SSLP) markers have been intercalated among gene-based markers including six anchor loci on mouse Chr 4 to assemble this map. Marker order and genetic distances are similar to the composite genetic linkage map compiled from crosses between a variety of other inbred and feral mouse strains. Transmission ratio distortion in favor of feral alleles is apparent for a region of distal MMU 4. In addition, the misty phenotype is more fully penetrant in the present backcross than in other reported interspecific and intersubspecific crosses. Backcrosses employing inbred Mus musculus musculus strains may allow reliable phenotyping and mapping of mouse mutations displaying complex phenotypes with incomplete and/or ambiguous penetrance on other feral genetic backgrounds.