Witch nail homozygotes develop very long toenails on all digits by 2 months of age. The nail bed is normal but the nail is thickened and elongated. X-rays of 5 homozygotes indicated the presence of additional caudal vertebrae in some but not all mutants.
The witch nails mutation arose spontaneously in the MRL/MpJ-Faslpr/J strain at The Jackson Laboratory in 2001. This mutation was backcrossed onto the C57BL/6J background and sperm was cryopreserved from homozygous males at generation N5.
|Allele Name||witch nails|
|Allele Type||Spontaneous (Not Specified)|
|Gene Symbol and Name||Krt90, keratin 90|
|Strain of Origin||MRL/MpJ-Faslpr/J|
|Molecular Note||This spontaneous 7 base pair duplication insertion of AGCCTGT in exon 9 causes a serine to arginine substitution at amino acid 476 followed by a frameshift leading to 36 novel amino acids and then a premature stop codon.|