Studies of a spontaneous lethal mutation at the albino locus in SELH/Bc mice

We report a new mutation at the albino locus in SELH/Bc mice. The mutation arose spontaneously in a male mouse that appeared to be a somatic and germ line mosaic for a new albino (c) allele, provisionally named cBc. The mutation is a recessive lethal, causing embryonic death soon after implantation. We have shown that there is no detectable activity of the Mod-2 allele in cis with the mutation and conclude that the mutation is probably a deletion that includes the c locus, the Mod-2 locus, the intervening 2 cM, and at least one locus essential for postimplantation embryonic survival, either proximal to the c locus or distal to the Mod-2 locus. This new mutation is similar to most previously reported spontaneous mutations at the albino locus in that it arose in a somatic and germ line mosaic mutant animal but differs from them in that it is an embryonic lethal when homozygous and is apparently a deletion. SELH/Bc mice appear to have a high mutation rate. This lethal albino mutation that appears to be a postmeiotic deletion should be useful in the search for the mechanism of mutagenesis in SELH/Bc mice. It may also be useful in mapping essential genes in the c-locus region.