Dominant white

Dominant white is a group of genetically related coat color conditions in the horse, best known for producing an all-white coat, but also for producing some forms of white spotting and white markings. Dominant white horses are born with unpigmented pink skin and white hair with dark eyes, although the amount of white hair or spotting can vary depending on which genetic mutation is involved. Dominant white is a rare condition, and under normal conditions, at least one parent must be dominant white to produce dominant white offspring. However, most of the currently-known alleles of dominant white can be linked to a documented spontaneous mutation in a single ancestor.

Dominant white can occur in any breed, and has been studied in many different breeds. Two color breeds, the American White Horse and Camarillo White Horse are characterized by their dominant white coats.

There are many different forms of dominant white; in genetics, as of 2013^[update] they are labeled W1 through W20. All known dominant white coat colors are associated with the KIT gene. As the name suggests, these known white coats are inherited dominantly, meaning that a horse only needs one copy of a W allele to have the white or white spotted coat.

Dominant white is genetically distinct from Sabino and both genetically and visually distinct from gray and cremello. Dominant white is not the same as lethal white syndrome, nor are dominant white horses "albinos". Albinism has never been documented in horses. Some forms of dominant white are thought to result in nonviable embryos when a zygote has two W alleles (is homozygous). However, this has not been verified for all dominant white genetic variations.

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