List of cat body-type mutations

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This article gives a selection of cat body type mutant alleles and the associated mutations with a brief description.

Tail types

Jb

Manx tailless gene, there are no associated skeletal disorders and the gene is not associated with lethality.^[2]

M

organ defects. Because it was discovered in naturally occurring populations of cats, the Manx gene could confer some kind of selective advantage to the cats, or it may simply be an example of the founder effect. The trait also occurred and died out in Cornwall (peninsular England),^{[citation needed]} but persisted in the Isle of Man population where outbreeding was not frequent due to isolation.^[3] Shortened tails, most of which are indistinguishable from the Japanese Bobtail or the variably expressed Manx mutation, may occur sporadically in any cat breed or mixed-breed population. However, some may be novel mutations that have not been investigated. There are multiple types of curly-tailed cats whose tails loop over the back or form tight corkscrews. One such mutation has been developed into the American Ringtail, but others have been regarded as curiosities and not perpetuated. The gene(s) responsible have not been fully investigated. However, a research study is under way at UC Davis under the guidance of Leslie A. Lyons, currently at the University of Missouri.^[4][5]

Mk

Toy and Teacup Persians),^[6] dwarf cats suffer from a genetic mutation called pseudoachondroplasia (dwarfism without enlarged heads), a type of osteochondrodysplasia (bone and cartilage disorder). These genetic disorders of bone and cartilage are typically manifested as abnormal bone shape, poor growth or lack of growth, bowing of the limbs to the side – front legs are more likely to be affected, and spinal malformations. The disorder leaves the cat with a full-size body, but disproportionately short and thick legs. Dwarf cats often suffer from spinal disorders, such as lordosis (excessive curvature of the spine) and pectus excavatum (hollowed chest).^[7] As with human dwarfism, there are still a lot of unknown mysteries in the science behind feline dwarfism. It is found that achondroplasia

in humans is the result of the FGFR3 gene.

Sh

Split Foot gene (Syndactyly). A dominant gene that reduces the number of toes resulting in a "lobster-claw" appearance. This is considered an undesirable mutation.

Polydactyly

There are probably many genes, both dominant and recessive, that cause polydactyly in cats. Most cases of polydactyly in cats are perfectly harmless.

Pd

Thumb-cat polydactyly gene. The Pd gene (dominant with incomplete penetrance) causes the benign, pre-axial form of polydactyly where one or more extra toes occur near the

opposable thumbs (in the thumb-cat form of polydactyly) give them a survival advantage.^{[citation needed]} Ernest Hemingway collected polydactyl cats, and the descendants of his pets may still be found at the Ernest Hemingway House in Key West.^{[citation needed}

]

Cu

American Curl gene (dominant). Cats with this gene have ears that start out normal, but gradually curl backwards. So far, no major harmful defects have been associated with this gene, however, due to the more exposed inner ear regular cleaning is required to prevent infection. Curled ears have also been observed in free-roaming cats in the Greek islands and in a cat in Australia.

Australian Curl

a curl-eared mutation occurred in a female stray cat in Australia, but was not inherited by her offspring. When the original cat became ill, necessitating spaying, it was impossible to test-mate her sons back to her to identify a possibly recessive curled-ear mutation. ^{[citation needed]}

Fd

Scottish Fold gene (dominant with incomplete penetrance). Cats with this gene have ears that curl forward. There are different degrees of folding, and more genes may be involved in the expression of the Fd gene. This gene is associated with bone and cartilage defects such as thickened tail and swollen feet. The homozygous form (FdFd) causes severe osteochondrodysplasia. Because of this, many breeders only breed folds to non-folds (straights) to avoid homozygous folds. However, heterozygous folds may also develop osteochondrodysplasia of lesser severity.

Sumxu or Chinese Lop-Eared Cat

extinct Chinese Lop-eared cat breed reported between 1700 and 1938 around

Peking

, most descriptions are based on a specimen in a German museum. The mode of inheritance of its pendulous ears is not known (the name Sumxu results from mistranslations and actually refers to a variety of marten).

Four ears

a recessive mutation that produced four

pinnae or ear flaps (the additional pinnae did not lead to additional ear canals and organs of hearing). In a group of four-eared cats studied in 1957, in addition to duplicated ears, the eyes were reduced in size, the jaw was slightly undershot and the cats were relatively inactive and lethargic. Researchers believed that the functioning of the brain was affected. Breeding data indicated it was most often lethal with kittens dying in utero. The majority of recently reported four-eared cats have been healthy with various ear configurations suggesting other genes were involved or developmental abnormalities rather than hereditary factors.^[10]

Rounded ears

a rounded ears mutation occurred in a cat in Italy and is being assessed for breed potential. A similar mutation occurred among free-roaming cats in Texas, but died out. The ears have a rounded, rather than pointed, shape. ^[citation needed]

Hairlessness

Sphynx cat

a

Dwelf and Elf

, which all bear the same hairless genetic mutation.

Donskoy

or Don Sphynx, is another hairless cat but is not related to the Sphynx, and its hairlessness is caused by a dominant instead of recessive mutation.^[12] The Peterbald is related to the Donskoy and bears the same dominant hairless mutation.

Miniature-sized

A germ-cell mutation occurred in a male Persian cat called Treker in 1995, resulting in diminutive, but healthy and normally-proportioned, offspring. Treker and the females with which he was mated were normally sized, but 75% of the kittens sired by Treker inherited diminutive stature, but of normal proportions. The gene was found to be dominant and the diminutive offspring were sold as teacup or toy Persians.

Many of the major cat registries do not allow the registry and breeding of cat breeds which bear certain of these genetic mutations, nor recognise them, due to concerns about the animal’s welfare.

Breeding with parent animals that bear hypertype mutations is effectively banned in Europe under the European Convention for the Protection of Pet Animals:^[14]

Any person who selects a pet animal for breeding shall be responsible for having regard to the anatomical, physiological and behavioural characteristics which are likely to put at risk the health and welfare of either the offspring or the female parent.

— Chapter II Article 5

Since 2014, it is illegal in the Netherlands to breed with parent cats which bear genetic mutations or other physical abnormalities that cause health or welfare issues in their offspring.^[15][16] Examples of these genetic mutations and physical abnormalities are dwarfism, the lack of protecting fur in hairless cats, and fold-eared cats.

Furthermore, several countries or states have prohibited breeding with certain of the genetic mutations in cats, including Scotland,^[17][18] Victoria and the Australian Capital Territory (Australia),^[19][20] Austria,^[21][22] and Flanders (Belgium).^[23]

References