Mutations at the Mitf locus affect eye size, pigmentation, and the capacity for secondary bone resorption. Mice homozygous for the white allele (MitfMi-wh) display an overall absence of pigment cells with the exception of the retina which expresses a few giving the eye a small amount of pigment. Homozygotes white mutant mice show slight microphthalmia but normal skeleton. Mice heterozygous for the microphthalmia (MitfMi) mutation have less iris pigment than wildtype and often have white spotting on the belly, head, and tail. Homozygous mutant mice have small eyes and are devoid of pigment in the eyes, inner ear, and skin. Homozygotes are deaf at an early age. There is a decrease of mast cells in the spleen and gut. Most homozygotes die around weaning but some may live for several months. There is a deficiency of secondary bone resorption (osteopetrosis) and the incisors fail to erupt. Immunological defects include decreased macrophage chemotac...
Read More +Genetic Background | Generation |
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000664 C57BL/6J |
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Allele Type | Gene Symbol | Gene Name |
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Other | Mitf | melanogenesis associated transcription factor |
Allele Type | Gene Symbol | Gene Name |
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Spontaneous | Mitf | melanogenesis associated transcription factor |
Mutations at the Mitf locus affect eye size, pigmentation, and the capacity for secondary bone resorption. Mice homozygous for the white allele (MitfMi-wh) display an overall absence of pigment cells with the exception of the retina which expresses a few giving the eye a small amount of pigment. Homozygotes white mutant mice show slight microphthalmia but normal skeleton. Mice heterozygous for the microphthalmia (MitfMi) mutation have less iris pigment than wildtype and often have white spotting on the belly, head, and tail. Homozygous mutant mice have small eyes and are devoid of pigment in the eyes, inner ear, and skin. Homozygotes are deaf at an early age. There is a decrease of mast cells in the spleen and gut. Most homozygotes die around weaning but some may live for several months. There is a deficiency of secondary bone resorption (osteopetrosis) and the incisors fail to erupt. Immunological defects include decreased macrophage chemotactic responses, impaired proliferative responses to B cell and T cell mitogens, diminished responses in vitro to T-dependent and T-independent antigens and reduced NK cell activity. Compound heterozygotes (MitfMi-wh/MitfMi) closely resemble white homozygotes (MitfMi-wh/MitfMi-wh) but their eyes are slightly more pigmented and not as small.
The white spontaneous mutation (MitfMi-wh) was found among offspring of a cross between the DBA and C57BL strains. The microphthalmia (MitfMi) was found among descendants of an irradiated male.
Allele Name | microphthalmia |
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Allele Type | Other |
Allele Synonym(s) | m; mi |
Gene Symbol and Name | Mitf, melanogenesis associated transcription factor |
Gene Synonym(s) | |
Strain of Origin | Not Specified |
Chromosome | 6 |
General Note | This mutation produces an osteopetrosis that resembles human osteopetrosis more than that produced by Ctsfop. MitfMi mutant mice have normal levels of M-CSF and its receptor. Osteoplasts are produced, but are unable to function normally in bone resorption (J:22788). Combination heterozygotes of MitfMi-wh/MitfMi show some interallelic complementation in that the heterozygote of the two alleles is more nearly normal than either homozygote (J:12967). MitfMi-Or/MitfMi mice resemble homozygous MitfMi-Or (J:15060). |
Molecular Note | This mutation was identified during an irradiation experiment, but it is not known whether it was induced in the treated male or spontaneously arose in an untreated mate. RT-PCR analysis identified a 3 nucleotide deletion in the transcript that results in a loss of one of four conserved arginine residues in the basic domain of the encoded protein. This mutation is predicted to affect the ability of the protein to bind DNA. |
Allele Name | white |
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Allele Type | Spontaneous |
Allele Synonym(s) | Miwh; mitfwh |
Gene Symbol and Name | Mitf, melanogenesis associated transcription factor |
Gene Synonym(s) | |
Strain of Origin | (C57BL x DBA)F1 |
Chromosome | 6 |
General Note | Combination heterozygotes of MitfMi-wh/MitfMi, MitfMi-wh/MitfMi-b, and MitfMi-wh/MitfMi-ws show some interallelic complementation in that the heterozygote of the two alleles is more nearly normal than either homozygote (J:12967, J:19656). MitfMi-b/MitfMi-wh agouti mice are light cream with white spots and ruby eyes (J:15061). |
Molecular Note | T-to-A transversion at bp 764, which leads to an isoleucine to asparagine substitution at amino acid 212 in the encoded protein (p.I212N). This mutation is in the basic region of the protein. |
When using the B6.Cg-MitfMi-wh/MitfMi/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #000158 in your Materials and Methods section.
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Heterozygous for Mitf<Mi-wh> or Mitf<Mi> |
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