Insertional Mutation of the Hairless Locus on Mouse Chromosome 14

Crosses between heterozygous transgenic mice from line 5053 resulted in offspring with progressive, irreversible hair loss starting at day 10, accompanied by thickened, plicated skin. Histological analysis showed a lack of normal hair follicles and the presence of intradermic cystic structures filled with keratinaceous material. Affected animals were homozygous for the transgene insertion, and their phenotype resembled the rhino allele at the hairless locus on Chromosome 14. Complementation tests and linkage analysis confirmed that the transgene disrupted the hairless locus. Older affected mice developed impetigo-like skin eruptions, suggesting immune deficiencies. The transgenic allele hr TgN5053Mm was deemed useful for identifying the transcription unit of the hairless locus.