Color: “Splashed white” can manifest as a wide blaze, sometimes covering the whole face, and is often associated with blue eyes. Long white socks and variable belly spotting is also common. Horses with a combination of Splashed White alleles may be completely or nearly completely white.
Samples Accepted: Blood, Hair
Locus Information: multiple
Test Information: Mutations in several genes may cause the splashed white phenotype; when a horse has mutations in more than one, a more extreme white phenotype may occur.
SW1: Test # H209: This test detects a mutation in the MITF core promoter, and has been found in many breeds, including the Quarter horse, Thoroughbreds, Trakehner, Icelandic Horse, Miniature Horse, Shetland Pony and others.
SW2: Test # H210: This test detects a single base pair change in exon 2 of the PAX3 gene. This mutation is found in some Quarter Horse and Paint horse lines. No homozygotes with this mutation have been identified, leading to the hypothesis that homozygosity may be embryonic lethal.
SW3: Test #H211: This test detects a deletion in exon 5 of the MITF gene. This mutation is found in some Quarter Horse and Paint horse lines. No homozygotes with this mutation have been identified, leading to the hypothesis that homozygosity may be embryonic lethal.
Hauswirth, R., Jude, R., Haase, B., Bellone, R.R., Archer, S., Holl, H., Brooks, S.A., Tozaki, T., Penedo, M.C., Rieder, S., Leeb, T.: Novel variants in the KIT and PAX3 genes in horses with white-spotted coat colour phenotypes. Anim Genet 44:763-5, 2013. Pubmed reference: 23659293. Doi: 10.1111/age.12057.
Hauswirth, R., Haase, B., Blatter, M., Brooks, S.A., Burger, D., Drögemüller, C., Gerber, V., Henke, D., Janda, J., Jude, R., Magdesian, K.G., Matthews, J.M., Poncet, P.A., Svansson, V., Tozaki, T., Wilkinson-White, L., Penedo, M.C., Rieder, S., Leeb, T.: Mutations in MITF and PAX3 cause “splashed white” and other white spotting phenotypes in horses. PLoS Genet 8(4):e1002653, 2012. Pubmed reference: 22511888. Doi: 10.1371/journal.pgen.1002653.
Further information is available at the Online Mendelian Inheritance in Animals website.