A Cornish Rex is a breed of domestic cat. The Cornish Rex has no hair except for down. Most breeds of cat have three different types of hair in their coats: the outer fur or "guard hairs", which is about 5 cm long in shorthairs and 10 cm+ long in longhairs; a middle layer called the "awn hair"; and the down hair or undercoat, which is very fine and about 1 cm long. Cornish Rexes only have the undercoat. Cornish Rex are prone to hair loss and many will develop a very thin coat or even go bald over large parts of their body. The curl in Cornish Rex fur is caused by a different mutation and gene than that of the Devon Rex. It originates from Cornwall, Britain.
The coat of a Cornish Rex is extremely fine and sometimes curly. Their light coat means that they are best suited for indoor living in warm and dry conditions, as they are sensitive to low temperatures. Cornish Rexes like to stay warm places such as computer monitors, light bulbs, laps and shoulders.
The breed is sometimes referred to as the Greyhound of the cats, because of the sleek appearance and the galloping run characteristic of the breed. These cats tend to stay playful and kittenish throughout their long lives. Some Cornish Rexes like to play fetch, race other pets, or do acrobatic jumps. The Cornish Rex is an adventurous cat and is very intelligent. It can readily adapt to new situations and will explore wherever it can go, jumping into refrigerators, examining washing machines, etc. The Rex is extremely curious, seeks out the company of people and is friendly towards other companion animals. It is a suitable pet for timid children.
Cornish Rex cats come in a wide variety of coat colours and patterns, outlined in the breed standard: solids, including white, black, chocolate, orange and the dilutes blue, lilac and cream; all forms of tabby including classic, mackerel and ticked tabbies, bicolor "tuxedo" coat in many colours, tortoiseshell, "smoke" colours and the colour-point pattern standard in the Siamese breed.
In 2013 researchers identified the mutation that defines the Cornish Rex breed. Genome-wide analyses were performed in the Cornish Rex breed and in 11 phenotypically diverse breeds and two random bred populations. A gene on chromosome A1, the lysophosphatidic acid receptor 6 (LPAR6), was identified to have a 4 base pair deletion. This induces a premature stop in the receptor which is absent in all straight haired cats analyzed. LPAR6 encodes a receptor essential for maintaining the structural integrity of the hair shaft. In humans LPAR6 mutations result in a wooly hair phenotype.