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Dominant White 37 (W37)

Gene or Region: KIT

Reference Variant: T

Mutant Variant: TA

Affected Breeds: Anglo-Arab

Research Confidence: High - Mutations in KIT have been well-documented to cause white spotting in both the horse and other species

Explanation of Results: W37/W37 = homozygous for Dominant White 37, white markings expressed W37/n = heterozygous for Dominant White 37, white markings expressed n/n = no variant detected

General Description for Dominant White 37 (W37) "Magic"

Dominant White 37 (W37) "Magic" is currently found in Anglo-Arabs and may result in white stockings, belly markings, and facial markings with possible blue eyes.

W37 Discovered In: Viconte des Neiges, Anglo-Arab stallion

W37 Phenotype: White stockings, belly markings, and facial markings

Gene Information

KIT is a tyrosine kinase receptor that is vital for normal development. Mutations in other species have led to white spotting, anemia, sterility, and certain types of tumors. However, no negative health effects associated with dominant white have ever been documented in the horse. The various W alleles encompass a variety of mutations, all resulting in changes to the encoded protein.

References

Obradovic NA, McFadden A, Martin K, Vierra M, McLoone K, Martin E, Thomas A, Everts RE, Brooks SA, Lafayette C. "Three Novel KIT Polymorphisms Found in Horses with White Coat Color Phenotypes." (2025) Animals. 15(7), 915; 15(7), 915. https://www.mdpi.com/2076-2615/15/7/915.

Haase B et al., “Allelic heterogeneity at the equine KIT locus in dominant white (W) horses.” (2007) PLoS Genet. 3: e195.

Haase B et al., “Seven novel KIT mutations in horses with white coat colour phenotypes.” (2009) Anim Genet. 40: 623-9.

Holl H et al., “De novo mutation of KIT discovered as a result of a non-hereditary white coat colour pattern.” (2010) Anim Genet. 41: 196-8.

Haase B et al., “Five novel KIT mutations in horses with white coat colour phenotypes.” (2011) Anim Genet. 42: 337-9.

Hauswirth R et al., “Novel variants in the KIT and PAX3 genes in horses with white-spotted coat colour phenotypes.” (2013) Anim Genet. 44: 763-5.

Holl H et al., “A novel splice mutation within equine KIT and the W15 allele in the homozygous state lead to all white coat color phenotypes.” (2017) Anim Genet. DOI: 10.1111/age.12554

Durig N et al., “Whole genome sequencing reveals a novel deletion variant in the KIT gene in horses with white spotted coat colour phenotypes.” (2017) Anim Genet. In press.