White horses have appeared from time to time on the American turf since White Beauty became the first officially registered white in The Jockey Club's records. Foaled in 1963, the daughter of Ky. Colonel carried a mutant allele of the KIT gene now designated as W2 (for "dominant white #2," one of 20 known dominant white alleles). The mutation has varying effects, so that a foal that carries it may range from a loudly marked horse with a partly white coat to pure white.
A daughter of Devil His Due, Beautiful Devil is the latest white winner from White Beauty's family, which is also responsible for the white winners Patchen Prince, The White Fox and Chief White Fox. Beautiful Devil's dam Spot of Beauty (by Skip Away) is also registered as white and was also a winner.
Although White Beauty's family descends from 1922 Coaching Club American Oaks winner Prudish, none of this family have come close to stakes level, and Beautiful Devil doesn't look like a runner with stakes potential at this point; she is already 3, and her recent maiden win was at Belterra Park in Ohio. In fairness, the mares of this line have generally been bred to relatively modest sires, and there is also a tendency for unusually colored Thoroughbreds to be diverted to sporthorse lines. It doesn't have to be that way, though. The Japanese mare Yukichan, a white by 2001 Japanese champion dirt male Kurofune (registered as gray/roan) from the white Sunday Silence daughter Shirayukihime, was a multiple stakes winner in 2008-2010.
Yukichan has no connection to the White Beauty family; her color and her dam's appear to be due to a spontaneous mutation. This also appears to be the case for Turf Club (by Trust N Luck), the dam of Passionforfashion, who is a white with numerous chestnut spots and a chestnut mane and tail. As least as of 2013, Turf Club had not been DNA typed to determine whether her color comes from one of the dominant white variations of KIT or from the sabino gene, a different allele of KIT which can also result in white or mostly-white coloring and which is responsible for the chrome of Turf Club's chestnut half sister Adorable (by Anet). Old Fashioned, the sire of Passionforfashion, is also a known sabino, further clouding the source of Passionforfashion's striking coloring.
How much ability Passionforfashion has is still unknown, but she is said to be a good mover and trainer Doug O'Neill is hoping she'll be ready to start at the Del Mar meeting. It will certainly be interesting to see if this horse of a different color has what it takes to become the first white North American stakes winner.