W5 is one of the many mutations of the KIT gene that cause the Dominant White phenotype.
Alternate names
Dominant White 5, White spotting W5
Symbol
W5
Breeds known to carry this mutation
Thoroughbreds related to the founder Puchilingui, who was born in 1984.
Inheritance pattern
Autosomal dominant
Description
W5 causes its carriers to have a significant amount of white. The appearance can range from a sabino-like pattern to the horse being completely white.
Interpretation of results
n/n: Horse does not carry the W5 mutation
W5/n: Horse carries one copy of the W5 mutation and will have a significant amount of white in its coat. This can range from a sabino like pattern to being completely white. It will pass the W5 mutation on to approximately half of its offspring.
W5/W5: Horse carries two copies of the W5 mutation. Please note that this is a theoretical genotype, and no horse has been identified as carrying two W5 mutations. It is suspected that embryos carrying two W5 mutations are not viable and die early in the pregnancy.
Reference
Haase et al. Seven novel KIT mutations in horses with white coat colour phenotypes. Animal Genetics 2009; 40:623-629. doi:10.1111/j.1365-2052.2009.01893.x