Knowledge of the most frequently encountered inherited and genetically determinate anomalies in animals is efficient for cat-fancies, and especially fro professional breeders. We begin the publication of reference book of the most common anomalies.
Domestic cat has 19 pairs of chromosomes. 18 of them called autosomes are similar for both sexes. The last pair, sexual, is different in males (XY) and females (XX). Each chromosome consists of more than 25000 genes. Though they assemble into many combinations, only some of them affect the characteristics of a breed exterior and its' variants. Any disruption in chromosome construction or their number somehow in evident or concealed manner changes the work of organs and systems in an organism. Every year more and more new genetic and inherited disorders appear in the cat population as a whole and in certain breeds in particular. Some of these mutations represent no danger for an animal health, other may cause serious diseases, third appear to be a specific characteristic of breed.
Using in private life and in industry different chemical substances that are mutagenes (i.e. they cause inherited changes - mutations), gives rise to active accumulation of mutations in a gene pool of cat population as a whole and makes systematic pure breeding appreciably complicated.
Genetically determined modifications in skin
Skin asthenia - discovered more than 20 years ago, occurs in dogs, minks, sheep and cattle too. It's a dominant pathology. Caused by a production of defected collagen that makes skin excessively delicate, elastic and velvety by touch, forms folds on limbs, hangs from the sides of the body and chest, easily stretches and likes like "second-hand". A recessive autosomic variant of skin asthenia have been discovered and occurs in Siamese cats and derived breeds only. Given disorder is also called dermatoproxy, or hereditary skin fragility because skin is easy to torn, forming rough scars after healing. Homozygous combination is lethal.
Lentigo - absolutely safe skin defect representing hyperpigmented (dark) spots less than 1 mm in diameter. Occurs in red (creamy) male cats alone. One is to suppose that this defect be linked to color. The way of inheritance is unknown.
Long hairs (l): non-anomaly; "useful" mutation. Originates from a polygenic inheritance. Occurs in Persians, exotic, Angora and other longhair breeds.
Wiry hairs (Wh): a dominant mutation causing a wire rigidity of hair. IS regarded to be a breeding characteristic for an American Wiry-haired cat.
Sparse hair around eyes (sf): hair becomes weeded out and gets thin around eyes along with accumulating of a typical brown exsudate around cat's eyes and mouth. As a rule, vibrissas are bent. It's a recessive mutation and has no clinical interest.
Hypotrichosis (sphinx-mutation of hair) - weeding out of hair down to it's disappearing. It's a recessive defect known fore more than 50 years. Three mutant genes have been discovered that are responsible for absence of hair (h, hd, hr).
Popular in USA Canadian has hr mutation. Some years ago a dominant mutation in cats had been found in Russia, on Don, where a new breed - Don Bold (Don Sphinx) has been standardized. One of variants of the disorder is inherited hypotrichosis occurring only in Devon-rexes and Siamese. Hair gets thin and comes out in kittens by age of 2 weeks. IN some kittens hair grows again by age of 8-10 weeks, but comes out again by 6 months. Defect is passed through an autosomic-recessive way.
Rex-mutation of hair - displays itself as a wavy hair in kittens, later hair gets curly. All rex breeds represent this mutation. Four types of rex-mutations are known: Cornish-rex (r), Devon-rex (rc), Oregon-rex (ro), and Dutch-rex (Rd). Today another two shorthaired rex-mutations on Ural and one longhaired rex-mutation in Persian cats in Czech have been found.
Larissa Voronina, candidate of medicine, Magazine "Droug"
Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).