W20 white markings (W20)
W20 is a version of the KIT gene that is thought to cause relatively subtle white markings such as a blaze and socks - and sometimes even less white. It has a white-increasing effect when it is inherited in combination with other white marking genes, particularly sabino 1 and the other W genes.
W20 has been found in a very wide range of horse breeds. The following are just some of the horse and pony breeds where some individuals have tested positive to W20: Thoroughbreds, Welsh Ponies, Quarter Horses, Appaloosas, Warmbloods, Gypsy horses, Clydesdales, Noriker, Miniature Horses... the list goes on.
If your horse has a blaze and one or more socks, or perhaps a few white belly spots that have not been explained by other white marking genes, test for W20 as well as sabino 1.
Gene or region and technical reference
Gene: KIT (causative). Reference: Hauswirth et al. (2013)
n. Test developed using animal controls.
W20. Test developed using animal cases.
Fred, a Warmblood, is homozygous for W20. He has four socks, a blaze, a belly splash and birdcatcher spots.