OMIA:000209-9793 : Coat colour, dominant white in Equus asinus (ass (donkey))

In other species: dog , domestic cat , horse , pig , llama , taurine cattle , goat , rabbit , domestic yak , alpaca , raccoon dog , Arctic fox

Categories: Pigmentation phene

Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 172800 (trait) , 164920 (gene)

Links to MONDO diseases: No links.

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal dominant

Considered a defect: no

Key variant known: yes

Year key variant first reported: 2015

Cross-species summary: The dominant white gene is one of a number of genes that regulate normal growth and proliferation of cells. In fact, it encodes a protein that protrudes through the cell membrane, relaying 'messages' across the membrane, from outside to inside the cell. The transmembrane domain of the protein is a receptor for a growth factor (a protein produced by one type of cell, that acts on another type of cell). The domain inside the cell has tyrosine kinase activity. When a growth factor binds to the receptor on the outside of the cell, this stimulates tyrosine kinase activity inside the cell, which sets off a cascade of phosphorylations, resulting in activation of transcription factors, which in turn activate genes, resulting in multiplication of stem cells, including melanocyte precursor cells, in the developing embryo. This whole process is known as a signal transduction pathway. During embryonic development, the melanosome precursor cells migrate from the neural crest down either side of the body. Under normal circumstances, they eventually meet at the centre of the belly. The cells then proliferate in all directions until they meeting neighbouring cells, thereby filling up all available areas, resulting in a solid mass of melanocytes over the entire body. The dominant white allele produces a defective transmembrane protein which is unable to relay 'messages', resulting in a lack of melanocytes, and hence white coat colour. An interesting aspect of the dominant white gene is that if it is activated at the wrong time, the result can be excess and uncontrolled proliferation of stem cells; in other words, cancer. In fact, at some time in the past, a feline retrovirus (the Hardy-Zuckerman 4 feline sarcoma virus) 'picked up' (by transduction) a copy of the dominant white gene from a cat, and incorporated this gene into its own genome. When this retrovirus infects cats, it activates its own copy of the gene at inappropriate times, causing sarcoma - a malignant tumour of cells derived from connective tissue. Retroviral genes that cause cancer are called oncogenes. The original host version of an oncogene is called a proto-oncogene. Thus, the dominant white gene is actually a proto-oncogene. In this particular case, the oncogene was discovered and named v-kit (where 'v' indicates a viral version of the gene) long before its association with white coat colour was established. The corresponding proto-oncogene is called c-kit, where 'c' stands for cellular. After the discovery and cloning of v-kit in the feline retrovirus by Besmer et al. (1986; Nature 320:415-421), c-kit was identified and mapped first in humans, by Mattei et al. (1987; Cytogenetics and Cell Genetics 46:657 only), and then in mice (Chabot et al., 1988; Nature 335:88-89, 1988), where it was shown to be identical with the long-recognised white-spotting (W) locus. Three years later, Giebel and Spritz (1991; Proceedings of the National Academy of Sciences 88:8696-8699) showed that mutations at the c-kit gene in humans cause piebaldism, which is the human homologue of white spotting (see the MIM entry at the top of this page)

Molecular basis: Haase et al. (2015): a missense variant in exon 4 (c.662A>C; p.Tyr221Ser)

Genetic engineering: Unknown
Have human generated variants been created, e.g. through genetic engineering and gene editing

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
KIT v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog Equus asinus 3 NC_052179.1 (139842600..139924498) KIT Homologene, Ensembl , NCBI gene

Variants

By default, variants are sorted chronologically by year of publication, to provide a historical perspective. Readers can re-sort on any column by clicking on the column header. Click it again to sort in a descending order. To create a multiple-field sort, hold down Shift while clicking on the second, third etc relevant column headers.

WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.

Since October 2021, OMIA includes a semiautomated lift-over pipeline to facilitate updates of genomic positions to a recent reference genome position. These changes to genomic positions are not always reflected in the ‘acknowledgements’ or ‘verbal description’ fields in this table.

OMIA Variant ID Breed(s) Variant Phenotype Gene Allele Type of Variant Source of Genetic Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Inferred EVA rsID Year Published PubMed ID(s) Acknowledgements
150 Coat colour, dominant white KIT W missense Naturally occurring variant c.662A>C p.(Y221S) 2015 25818843

Cite this entry

Nicholas, F. W., Tammen, I., & Sydney Informatics Hub. (2015). OMIA:000209-9793: Online Mendelian Inheritance in Animals (OMIA) [dataset]. https://omia.org/. https://doi.org/10.25910/2AMR-PV70

Reference

2015 Haase, B., Rieder, S., Leeb, T. :
Two variants in the KIT gene as candidate causative mutations for a dominant white and a white spotting phenotype in the donkey. Anim Genet , 2015. Pubmed reference: 25818843. DOI: 10.1111/age.12282.

Edit History


  • Created by Frank Nicholas on 16 Apr 2015
  • Changed by Frank Nicholas on 16 Apr 2015