Russian Blue
In 2010, DNA analysis confirmed that Sphynx hairlessness was produced by a different allele of the same gene that produces the short curly hair of the Devon Rex (termed the "re" allele), with the Sphynx's allele being incompletely dominant over the Devon allele and both being recessive to the wild type. The Sphynx's allele is termed "hr", for hairless. The only allowable outcross breeds in the CFA are now the American Shorthair and Domestic Shorthair. Other associations may vary, and the Russian Blue is a permitted outcross in the Governing Council of the Cat Fancy (GCCF). In Europe, mainly the Devon Rex has been used for outcrosses.