Molecular basis for the rhino (hrrh-8J) phenotype: a nonsense mutation in the mouse hairless gene.

The hairless (hr) and rhino (hrrh) mutations are autosomal recessive allelic mutations that map to mouse Chromosome 14. Both hairless and rhino mice have a number of skin and nail abnormalities and develop a striking form of total alopecia at approximately 3-4 weeks of age. The molecular basis of the hairless mouse phenotype was previously found to be the result of a murine leukemia proviral insertion in intron 6 of the hr gene that resulted in aberrant splicing. In this study, we report a 2-bp substitution in exon 4 of the hr gene in a second allele of hr, rhino 8J (hrrh-8J), leading to a nonsense mutation. These findings document the molecular basis of the rhino phenotype for the first time and suggest that rhino is a functional knock-out of the hr gene.