Caracul-like recessive (calre): a new curly coat mutation mapping near the Krt2-6g locus on Chromosome 15
Son Yong Karst, Patricia F. Ward-Bailey, Leah Rae Donahue, Roderick T. Bronson, Kenneth R. Johnson, and Muriel T. Davisson
Source of Support: This research was supported by NIH/NCRR grant RR01183 to the Mouse Mutant Resources (M.T.Davisson, PI) and Cancer Center Core Grant CA34196.
Mutation (allele) symbol: calre
Mutation (allele) name: caracul-like recessive
Gene symbol:calre (probable allele of Krt2-6g)
Strain of origin: BKS.Cg-m+/+Leprdb/J
Current strain name: BKS.Cg-m+/+Leprdb/J-calre/J
Stock #:005736 (view JAX® Mice Data Sheet for additional information including Price and Supply Information) NOTE: as of 1-4-07 available cryopreserved from JAX® Mice or as DNA only from the Jackson Laboratory DNA Resource.
Phenotype categories: Hair
Abstract
A spontaneous recessive curly coat mutation has been identified and mapped to Chromosome 15 in the same position as the previously described mutations caracul (Krt2-6gCa) and caracul-like (Cal). A direct test for allelism was not set up between mice carrying the Ca or Cal mutations and mice carrying this new mutation, because both Ca and Cal are dominant alleles.
Origin and Description
The caracul-like recessive mutation was discovered by Leslie Haynes in 2004, in a production colony of BKS.Cg-m+/+Leprdb/J mice at the Jackson Laboratory. The curly coat of this spontaneous homozygous mutant mouse is recognized at 10-12 days of age when hair is fully covering the body. At 2 weeks of age the coat of homozygous mutants looks very curly, and the mutants also have curly vibrissae (see photo). After several weeks, the curly phenotype is reduced; the hair becomes fuzzy in appearance, and the vibrissae straighten out and appear normal (see photo). Some mutant mice have no whiskers at wean age. Also, in older homozygous and heterzygous mice more whiskers are lost, and homozygous mutants lose more hair as they age. Homozygous mutant mice live normal life spans and breed normally. The BKS.Cg-m+/+Leprdb/J-calre/J colony is maintained by mating homozygous x heterozygous or heterozygous x heterozygous mice. Descriptions of four dominant caracul-like mutants are also described on this web site: Cal4, Cal5, Cal6, and Cal7. This new calre mutation differs from the previously described Cal mutations in that it has a recessive mode of inheritance.
Genetic Analysis
This mutation has recessive inheritance as shown by mating a homozygous BKS.Cg-m+/+Leprdb/J-calre/J female mouse to an unrelated male +/+ CAST/Ei mouse. This mating produced all unaffected progeny proving the new mutation to be recessive. The unaffected F1 hybrids produced in this cross were then intercrossed, and 50 affected F2 animals were produced for linkage analysis. This new mutation was mapped to Chromosome 15, distal to D15Mit14 (1 recombinant/40 meioses tested) and non-recombinant with D15Mit16. The marker D15Mit14 is at the 99.7 Mb NCBIm34 position, D15Mit16 is at the 103Mb NCBIm34 position, and the original caracul mutation is positioned at the 101.7Mb NCBIm34 position.
Pathology
A pathological screen of two homozygous caracul-like recessive mutant mice revealed no gross lesions. Plucked hair samples taken from mutant mice showed that there is a normal distribution of hair types, but zigzag hairs have abnormal bends and kinks (see photo). Skin sections were histologically normal.
Hearing as assessed by ABR (auditory brainstem response) testing of two homozygous mutants and 2 controls at 3 months of age revealed moderate hearing loss in both homozygous mutant and control mice. A homozygous mutant tested at 7 months and another at 12 months of age were both deaf. This hearing loss is characteristic of the BKS.Cg-m+/+Leprdb/J background strain and not the result of the new mutation.
The eyes of 2 homozygous mutant mice were tested with an opthalamscope and were determined to be normal.
Discussion
Based on the similarity of the hair phenotype with caracul mutants (Krt2-6gCa) and the position on Chromosome 15, it is likely that caracul-like recessive is a remutation of the Krt2-6J gene.
Acknowledgements
The authors thank Heping Yu for ABR testing, Norm Hawes for the eye examination and Coleen Marden and Jane Maynard for excellent technical skills.
References
MGD
Mouse Genome Database (MGD) Mouse Genome Informatics Project, The Jackson Laboratory, Bar, Harbor, Maine. World Wide Web (URL: http://www.informatics.jax.org).
Ensembl
MGSC27.33c.1. Mouse Genome Sequencing Consortium
