Генетические мутации у кошек и выведение новых пород.

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Cats, like all living organisms, occasionally have mutations that affect their body type. Sometimes, these mutations are striking enough that humans select for and perpetuate them. However, in relatively small or isolated feral cat populations the mutations can also spread without human intervention, for example on islands. Cat breeders exploit the naturally occurring mutations by selectively breeding them in a small gene pool, resulting in the creation of new cat breeds with unusual physical characteristics. The term designer cats is often used to refer to these cat breeds. This can be distinguished phenotypically from the Manx cat mutation by the presence of kinking in the tail, often forming what looks like a knot at the distal end of the tail. Unlike the Manx tailless gene, there are no associated skeletal disorders and the gene is not associated with lethality. Cats with the heterozygous genotype (Mm) show severely shortened tail length, ranging from taillessness to a partial, stumpy tail.

Mk Munchkin or dwarf cat gene (dominant). Cats heterozygous for this gene (Mkmk) have shortened and thickened legs, because this gene causes dwarfism in cats. Cats with this mutation have lived naturally in feral populations worldwide. However, cats with this gene are also the basis for several intentionally selected breeds of dwarf cat. The Munchkin is the first created dwarf cat breed, which was used as a foundation stock for other “spin off” breeds, such as the Minskin, Minuet or Napoleon, 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). 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 dew claw. Often, the dew claw is converted into a thumb. There are occasional problems, such as fused claws or claws facing in the wrong direction, but, generally, this form of polydactyly is harmless. On the other hand, the "hamburger feet" polydactyly gene is associated with the gene for radial hypoplasia (RH). In a scandal in the late 1990s, an experimental breeder in Texas tried to perpetuate this deformity as the "Twisty Cat" breed. Mild RH can cause the post axial form of polydactyly – enlarged paws, extra three jointed toes on the outer, little toe side of the paws, and no thumb. 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.

Sphynx cat a breed of cat known for its lack of fur. Hairlessness in cats is a naturally occurring genetic mutation and the Sphynx was developed through selective breeding starting in the 1960s. This characteristic hairlessness is caused by a recessive mutation in the keratin 71 gene. Recently crossed experimental hairless cat breeds related to the Sphynx are the Bambino, 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. The Peterbald is related to the Donskoy and bears the same dominant hairless mutation.

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. Toy and Teacup Persians are a separate breed and not all cats advertised under those names result from Treker's dominant mutation. Most teacup and toy size Persian kittens raised now are descendants from Silver and Golden color division to reduce cat size and are in no way related to Treker.