Young Blonde Girl With A White Top Riding On The White Horse In The Nature

White colorings, whether white markings, white patterns or dominant white are collectively known as depigmentation phenotypes, and all are caused by areas of skin that lack pigment cells (melanocytes). Depigmentation phenotypes have various genetic causes, and those that have been studied usually map to the EDNRB and KIT genes. However, much about the genetics behind various all-white depigmentation phenotypes are still unknown.
• Dominant white
Dominant white is best known for producing pink-skinned all-white horses with brown eyes, though some dominant white horses have residual pigment along the topline. Dominant white is, as the name implies, a genetically dominant color. At least one parent must be dominant white and it does not "skip" generations because it is not recessive. Nonetheless, new variations or mutations producing dominant white do occur spontaneously from time to time. Dominant white is rare, but has occurred in many breeds. It has been studied in Thoroughbreds, Arabian horses, the American White horse and the Camarillo White horse. There are 11 identified variants of dominant white, each corresponding to a spontaneously-white foundation animal and a mutation on the KIT gene. No horse has been identified as homozygous dominant white, and researchers have suggested that at least some forms of dominant white results in nonviable embryos in the homozygous state. While homologous mutations in mice are often linked to anemia and sterility, no such effects have been observed in dominant white horses. Dominant white horses typically have white noses that can be subject to sunburn.