Researchers recently discovered a new genetic mutation in a Thoroughbred foal that was born with large portions of nonpigmented skin. Whether another horse with the same rare mutation will be born is unknown, but the discovery has fueled researchers' pursuit of knowledge about coat color-related genetics and its potential relationship to serious health problems or death.

Essential to skin pigment is the function of a particular multipurpose gene, called KIT (an acronym for the actual genes involved), which the researchers examined in the current study. The KIT gene specifies the genetic code for a special protein called a tyrosine kinase receptor, expression of which is essential for the proper development of a variety of cell types, including red blood cells, mast cells of the immune system, and melanocytes (pigment-producing cells located in the bottom layer of the skin).

"KIT mutations cause abnormal melanocytes that do not produce pigment in the skin," explained Heather Holl, BSc, a PhD student in the Department of Animal Science at Cornell University. "The result is horses with pink skin and white hair. The amount of affected skin varies and ranges from small patches of depigmentation to white over the entire body."

To date, researchers have identified 14 different mutations involving the equine KIT gene, including the Sabino-1 and Tobiano color patterns.

Holl explained, "We suspected a new mutation after the birth of a Thoroughbred colt with extensive white markings. Both the parents had only small white markings and the sire had over 400 registered offspring without a single recorde