Summary |
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Mutation origin |
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Mutation description |
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Phenotypes |
View phenotypes and curated references for all genotypes (concatenated display).
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Expression |
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Find Mice (IMSR) |
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Notes |
Tyrc, albino. This very old mutant was already known in Greek and Roman times. Hair and eyes are completely devoid of pigment (J:5436, J:5001, J:30725). The albino mutation affects the amount of tyrosinase, and thus of melanin, in pigment cells, but does not interfere with the production of pigment cells themselves (J:12173, J:13092). Melanocytes with melanosomes showing normal fine structure occur in the retina and hair follicles. Pigment granules are smaller and fewer than normal and completely lack melanin (J:5346, J:5001, J:30725). Tyrosinase is almost absent (J:12173).
Although Tyr is the structural gene for tyrosinase, some albino mutations may affect tyrosinase enzyme regulation rather than structure (J:6611), suggesting that these mutations affect tyrosinase inhibition (J:5346), presumably via control regions of the gene. All the mutant alleles are recessive to wild-type in phenotype, but heterozygotes with wild-type produce intermediate amounts of tyrosinase (J:12173).
Albino-locus mutants with lightly pigmented eyes have a reduced number of fibers of the optic nerve going to the ipsilateral lateral geniculate nucleus of the brain. This is probably a secondary effect of reduced tyrosinase activity or amount of pigment in the pigment epithelium, since genes at other loci that reduce eye pigmentation also cause the same anomaly (J:5436, J:6064).
Abnormal retinal pathways disrupted at the optic chiasm that occur in albinism can be corrected with a Tyr normal transgene (J:22320).
Lipofuscin is a terminal oxidation product pigment that accumulates with age. In a cross of C57BL/6J and BALB/cJ, which differ in cardiac deposition of the pigment, this trait segregated with albinism, and is controlled by the Tyr locus (J:15460).
Tyrc homozygotes do not perform as well as normal in a number of behavioral tests. It is likely that this effect is mediated, at least in part, by defective vision resulting from lack of retinal pigment (J:5470, J:5360, J:5378).
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References |
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Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Models of Human Cancer database (MMHCdb) (formerly Mouse Tumor Biology (MTB)), Gene Ontology (GO) |
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last database update 12/10/2024 MGI 6.24 |
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