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Why the Selkirk Rex has an unusual hair coat

Gandolfi B, Alhaddad H, Joslin SE, et al. A splice variant in KRT71 is associated with curly coat phenotype of Selkirk Rex cats. Sci Rep. 2013; 3: 2000.
Breed development in cats is often initiated by selection based on aesthetically pleasing coat pelage as occurred with the Selkirk Rex. The Selkirk Rex originated in the U.S. in 1987 when a rescued cat delivered a litter in which one female kitten (Miss DePesto) had a distinct soft woolly coat (rexoid-type coat). 

All Selkirk Rex trace their ancestry to this one cat with an average elapse of only 8.4 generations. Nine rexoid-type coat phenotypes are known in domestic cats, including Devon Rex, Cornish Rex, German Rex, Oregon Rex (extinct), Selkirk Rex, LaPerm, American Wirehair, Donskoy (and Peterbald), and Sphynx. Selkirk Rex, as well as LaPerm, American Wirehair and Donskoy, possess an autosomal dominant rexoid genetic trait; different from the other rexoid breeds in which the characteristic is genetically recessive.

Researcher at University of California, Davis and collaborators used a genome-wide case-control association study that included 9 curly coated Selkirk Rex and 29 controls comprised of straight-coated Selkirk Rex, British Shorthair and Persian. Validating an appropriate control group was a major feat in this study, which showed the Selkirk Rex belongs to a class termed “Persian-family”. 
A rexoid phenotype was localized to cat chromosome B4. A cluster of keratin candidate genes within the association region was recognized. Direct sequencing of four candidate genes eventually revealed a KRT71 gene splice variant to be associated with the Selkirk Rex hair texture. It has previous been shown that Devon Rex and Sphynx also have mutations in KRT71 further downstream from the mutation found in Selkirk Rex, leading to an autosomal recessive trait in these other rexoid breeds. This is the first time in cats that a mutation within KRT71 has been linked to an autosomal dominant form of curly hair coat. [GO]

FUNDING: This project was partially funded by Winn Feline Foundation grants W10-014 and W10-015.

See also: Filler S, Alhaddad H, Gandolfi B, et al. Selkirk rex: morphological and genetic characterization of a new cat breed. J Hered. 2012; 103: 727-33.

Gandolfi B, Outerbridge CA, Beresford LG, et al. The naked truth: Sphynx and Devon Rex cat breed mutations in KRT71. Mamm Genome. 2010; 21: 509-15.