Cocoa 8 Jackson, a new spontaneous mouse mutation in the Hps3 gene

Son Yong Karst, Patricia F Ward-Bailey, Leah Rae Donahue, Kenneth R .Johnson, and Muriel T Davisson

Source of Support: This research was supported by grants NIH/NCRR RR01183 to the Mouse Mutant Resource (M.T. Davisson, PI) and Cancer Center Core Grant CA34196.

Mutation (allele) symbol: Hps3coa-8J

Mutation (allele) name: cocoa 8 Jackson

Gene symbol: Hps3

Strain of origin: C57BL/6J

Current strain name: C57BL/6J-Hps3coa-8J/J

Stock #: 007711 (View JAX®Mice Data Sheet for additional information including Price and Supply Information) 

Phenotype categories: Coat color

 

Origin and Description

The recessively inherited cocoa 8 Jackson (Hps3coa-8J) mutation arose spontaneously and was found by Vicki Hutchinson in 2005 in a production colony of C57BL/6J mice at the Jackson Laboratory. Like previously described Hps3coa mutants, mice homozygous for the Hps3coa-8J mutation have a lighter coat color than littermate controls (See Photo) and can be recognized when their first coat of hair comes in at about 10 days of age. Heterozygotes have a normal C57BL/6J coat color (black). Both heterozygous and homozygous mice live a normal lifespan and breed well. The originally described coa mutants had prolonged bleeding associated with a platelet defect. Blood work was not performed on the new Hps3coa-8J mutants, so it is uncertain that they carry the platelet defect.

 

Genetic Analysis

Using standard MMR mapping protocols a linkage cross was performed by mating a female homozygous for the Hps3coa-8J mutation to a wild type CAST/Ei male mouse. The unaffected F1 progeny from this mating were intercrossed and produced 48 affected mice of which 21 were used for linkage analysis. The mutation was mapped to the region of Chromosome 3 where the Hps3coa is located, between D3Mit176 (NCBI 36 position 22.1 Mb) and D3Mit268 (NCBI 36 position 28.9 Mb). Because of the similarity of phenotype of Hps3coa mutants to this new mutation a direct test for allelism was performed. A female heterozygous for the Hps3coa-8J mutation was mated to a C3H/
HeJ-Hps3coa-7J/J male heterozygote. This mating produced 9 progeny of which 2 were affected with the coa phenotype proving allelism.

Pathology

A routine pathological screen of one homozygous Hps3coa-8J mutant mouse and a littermate control at 9 weeks age showed no gross abnormalities.

Hearing as assessed by auditory brainstem response (ABR) testing of one homozygous Hps3coa-8J mutant mouse at 12 weeks age revealed no hearing loss.

The eyes of one homozygous Hps3coa-8J mutant mouse at 8 weeks age were examined with an ophthalmoscope and showed a normal eye phenotype.

 

Acknowledgements

The authors thank Vicki Hutchinson for discovery of the mutant, Chantal Longo-Guess for hearing assessment, Norm Hawes and Ron Hurd for the eye examinations and Coleen Marden for excellent technical skills.