These mice possess loxP sites on either side of exon 8 of the targeted gene. Mice that are homozygous for this allele are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have exon 8 deleted in the cre-expressing tissue(s). When bred to a strain with Cre recombinase expression in mammary cells, or a strain with widespread Cre recombinase expression, this mutant mouse strain may be useful in studies of Bloom Syndrome. The Jackson Laboratory 2024, used with permission.