05-05-2023-1037 - Sphynx Cat (Wikipedia)

Two Sphynx cats, displaying breed variation in color, as well as body shape and size

Breeding

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.^[8] 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.^{[citation needed]} Other associations may vary, and the Russian Blue is a permitted outcross in the Governing Council of the Cat Fancy (GCCF).^[9] In Europe, mainly the Devon Rex has been used for outcrosses.^{[citation needed]} 

Genetics

The Sphynx's hairlessness is produced by a mutation in the same gene that produces the short curly coat of the Devon Rex.^[8] Moreover, it was found that the curly coat of Selkirk Rex cats is also associated with this gene.^[10]

The gene encodes keratin 71 (KRT71) and is responsible for the keratinization of the hair follicle. The Sphynx's mutation leads to a complete loss of function where the structure of the hair is damaged so that the hair can be formed but is easily dislodged. In the Devon Rex mutation, a residual activity of the protein still exists.^[8] The Selkirk Rex allele (sadr) is dominant over the wild type gene, which is dominant over the Devon Rex allele (re) and the Sphynx (hr), which forms an allelic series of : KRT71SADRE > KRT71+ > KRT71re > KRT71hr.^[10]

A male purebred Sphynx in the "mink" pattern. Like a pointed cat, the mink pattern also exhibits darker points: the ears, tips of tail, feet and nose. However, whereas the pointed pattern is entirely colorless everywhere else on the body, the mink coloration has some color throughout the body and just slightly darker points in adulthood. The mink pattern can be combined with any color.^[11]

Two Sphynx sleeping, black and white colors

Hypertrophic cardiomyopathy

The breed does have instances of the genetic disorder hypertrophic cardiomyopathy (HCM). Other domestic cat breeds prone to HCM include Persian,^[22] Ragdoll, Norwegian Forest cat, Siberian cats, British Shorthair and Maine Coon;^[23] however, any domestic cat including mixed breeds can acquire HCM.^[24] Studies are being undertaken to understand the links in breeding and the disorder.^[25] Cats are screened for HCM disease with echocardiography (ultrasound of the heart), as well as with additional tests determined by the veterinarian cardiologist including electrocardiogram (EKG, ECG), chest radiographs (X-rays), and/or blood tests.^[24]

https://en.wikipedia.org/wiki/Sphynx_cat