These mice carry a spontaneous mutation at the Ttc7 locus characterized by pathologic changes in the skin yielding a papulosquamous disease resembling human psoriasis.Read More +
Homozygous fsn mice suffer from hypochromic and normocytic anemia at birth which becomes more severe with age. The anemia makes the homozygous mice distinguishable as pups because of the pale color of ears and eyes. At 2 weeks of age focal epidermal hyperplasia and inflammation is evident with psoriasiform skin lesions becoming confluent and diffuse in 3-4 week old weanlings. The skin lesions progress to generalized alopecia and shedding of thick white scales. The gross lesions are accompanied by thickening and keratinization of the skin. A progressive paplosquamous disease ensues which is a model for some forms of psoriasis. fsn/fsn mice show hematocrit levels and red blood cell counts that are significantly decreased from birth through adulthood. Consequently the heart, liver and spleen become enlarged but the thymus weight is less than half normal. As the spleen enlarges, the mice also develop a potbellied appearance aiding in homozygous fsn identification. Gastric papillomas are found in the forestomach of fsn homozygotes but there is no papillomavirus associated with the lesions. Examination by scanning electron microscopy reveals a greatly thickened epidermis, sparsity of hairs and scale accumulations on the epidermis. Hair shaft and nail abnormalities are also present. Autoimmunity in homozygous fsn mice is manifested by glomerulonephritis accompanied by immune complex deposition in the kidneys, increased serum blood urea nitrogen levels, and the presence of circulating anti-double-stranded DNA autoantibodies.
The flaky skin mouse mutation, fsn, first arose as a spontaneous mutaion in A/J inbred mice in September 1984 at the Jackson Laboratory. The original mutant mice were runted and the gene was poorly penetrant. While intercrossing the (A/J X BALB/cByJ) fsn/+ parents produced a more vigorous offspring, maintenance was still difficult because of metabolic stress from compromised respiration. The breeding process was improved by grafting fsn/fsn ovaries to ovariectomized severe combine immunodeficiency (scid/scid) hosts followed by cycles of crossing to BALB/cByJ-+/+ males and intercrossing of fsn/+ F1 offspring. Neither fsn/fsn males or females will mate.
|Allele Name||flaky skin|
|Gene Symbol and Name||Ttc7, tetratricopeptide repeat domain 7|
|Strain of Origin||A/J|
|General Note||The skin disorder is a progressive papulosquamous disease resembling some forms of human psoriasis. The cutaneous phenotype can be transferred with bone marrow grafts to Prkdcscid homozygous mice (J:14506). Full thickness skin grafts to Foxn1nu homozygotes retain the psoriasiform phenotype in this host lacking T cells (J:18002). |
Phenotypic Similarity to Human Syndrome: Psoriasis
|Molecular Note||An ETn early transposon insertion of 183 bp occurred in intron 1`4, 57 bp upstream of exon 15.|
When using the flaky skin mouse strain in a publication, please cite the originating article(s) and include JAX stock #001723 in your Materials and Methods section.