| First Author | Ward-Bailey PF | Year | 2015 |
| Journal | MGI Direct Data Submission | Mgi Jnum | J:223505 |
| Mgi Id | MGI:5649260 | Citation | Ward-Bailey PF, et al. (2015) Witch nails (whnl): a new spontaneous mutation that causes very long toenails. MGI Direct Data Submission |
| abstractText | The new spontaneous, recessive mutation witch nails (whnl) was discovered in a colony of MRL/MpJ-Fas<lpr>/J mice at the Jackson Laboratory in 2001. All mice homozygous for the whnl mutation develop very long nails on all digits by two months of age. Histopathological examination of 10 homozygotes between the ages of 6 days and over a year showed no gross abnormalities in somatic organs. Serial sections through the paw show that the nail bed is normal but the nail is thickened and elongated. X-rays of 5 homozygotes showed some but not all homozygous mutant mice have additional caudal vertebrae with lateral processes. An ophthalmoscopic examination of the eyes and ABR threshold assessment of the hearing were done on two homozygous mutants and two control mice at four months of age and no abnormality was detected. Heterozygotes appear normal. Both homozygotes and heterozygotes breed and live a normal lifespan, but heterozygous intercrosses produced fewer than 10% homozygotes, significantly lower than the expected 25%. When backcrossed onto the C57BL/6J background the phenotype remains essentially the same. For linkage analysis, CAST/EiJ males were mated to females homozygous for whnl. The F1 hybrids from this initial cross were aged to two months and did not have long nails showing that whnl is a recessive mutation. The F1 hybrids were then intercrossed and the F2 progeny were scored visually when they were two months of age for the long nail phenotype. A genome sweep of this F2 population, including 55 homozygotes, found linkage of whnl to Chromosome 15 with D15Mit76. DNA samples were then typed for nine additional Chr 15 markers, which allowed us to position the whnl mutation distal to D15Mit148 and non-recombinant with D15Mit16, D15Mit79, and D15Mit35. We thank Coleen Kane for pathological techniques, the late Norman Hawes for the eye examinations and Heping Yu for the hearing assessment. This work was supported by NIH/NCRR grants RR001183 and OD010972-35 to the Mouse Mutant Resource. |
