|All the Pretty Horses|
|Coat color genes at work|
Edward R. Winstead
April 28, 2000
You go girl. After a string of magazine covers, Patchen Beauty made her racing debut at Churchill Downs in 1997: She finished fifth. That didn't stop a Saudi Arabian sheik from reportedly trying to purchase the rare white thoroughbred. According to a Kentucky newspaper, her owner told the sheik that Patchen Beauty was not for sale at any price.
Patchen Beauty comes by her good looks honestly. Her mother, Precious Beauty, and her maternal great-grandmother, White Beauty, had the trait. White thoroughbreds are so rare that the Jockey Club has registered only eleven since the 1890s.
"Most breeders and owners care about coat color," says Ann Bowling, a horse researcher at the University of California, Davis. Bowling has studied coat color genes for two decades. "The color of a horse is a complex trait that is due to the actions of a half-dozen or a dozen different genes," she says.
Bowling is an expert on the genetics of the overo pattern found in paint horses. Overo is loosely defined as any white spotting pattern that is not conventional markings, not tobiano and not appaloosa. Although popular among breeders, the overo coat is associated with a fatal genetic disease. A foal that inherits two copies of the overo gene is born white and will die of complications from intestinal tract abnormalities.
Scientists developed a DNA test to help breeders avoid producing lethal white foals. A version of the disease exists in humans and is characterized by a white forelock.
For more information on coat color genetics visit: http://www.vgl.ucdavis.edu
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