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The Color-Density Gene The third and last of the genes controlling the coat color is the color-density gene. This gene controls the uniformity of distribution of pigment throughout the hair and comes in two alleles: dense, "D", and dilute, "d".
The dense allele, "D", is wild, is dominant, and causes pigment to be distributed evenly throughout each hair, making the color deep and pure. A dense coat will be black, dark brown, medium brown, or orange.
The dilute allele, "d", is mutant, is recessive, and causes pigment to be agglutinated into microscopic clumps surrounded by translucent unpigmented areas, allowing white light to shine through and diluting the color. A dilute coat will be blue (gray), tan, beige, or cream.
The Eight Cat Colors All possible expressions of the color, orange-making, and color- density genes produce the eight basic coat colors: black, blue (gray), chestnut or chocolate (dark-brown), lavender or lilac (tan), cinnamon (medium brown), fawn (beige), red (orange), and cream.
Sex "BB Bb Bbl bb bbl blbl" ooDD Either Black Black Black Chestnut Chestnut Cinna ooDd Either Black Black Black Chestnut Chestnut Cinna oodd Either Blue Blue Blue Lavender Lavender Fawn oODD Female Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red Male Black Black Black Chestnut Chestnut Cinna oODd Female Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red Male Black Black Black Chestnut Chestnut Cinna oOdd Female Blu/Crm Blu/Crm Blu/Crm Lav/Crm Lav/Crm Fwn/Crm Male Blue Blue Blue Lavender Lavender Fawn OoDD Female Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red Male Red Red Red Red Red Red OoDd Female Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red Male Red Red Red Red Red Red Oodd Female Blu/Crm Blu/Crm Blu/Crm Lav/Crm Lav/Crm Fwn/Crm Male Cream Cream Cream Cream Cream Cream OODD Either Red Red Red Red Red Red OODd Either Red Red Red Red Red Red OOdd Either Cream Cream Cream Cream Cream Cream The brown and dilute colors are rarer (hence generally more prized) because they are recessive. A table of all possible combinations of the three genes controlling color will show all eight basic coat colors, among which are six female or twelve male black cats but only one female or two male fawn:
Note that although tortoiseshell females are two-color they introduce no new colors.
It may also be noted that red and cream dominate any of the true (black or brown) colors: a red coat is red regardless of whether the color gene is black, dark brown, or light brown. The color gene is masked by the orange-making gene. This, coupled with the fact that males are either red or non-red require that the color chart show "oO" and "Oo" as distinctly separate. A male has only the first of the two genes: "o" from "oO" or "O" from "Oo". In some texts, the orange- making genes are indicated as "o(O)" and "O(o)" to emphasize the sexual distinction.
The Albinism Gene The first of the color-conformation genes affect coat pattern is the albinism gene. This gene controls the amount of body color and comes in five alleles: full color, "C", Burmese, "cb", Siamese, "cs", blue- eyed albino, "ca", and albino, "c".
The full color allele, "C" is wild, is dominant, and produces a full expression of the coat colors. This is sometimes called the non- albino allele.
The Burmese allele, "cb", is mutant, is recessive to the full color allele, codominant with the Siamese allele, and dominant to the blue- eyed albino and albino alleles, and produces a slight albinism, reducing black to a very dark brown, called sable in the Burmese breed, and producing green or green-gold eyes.
The Siamese allele, "cs", is mutant, is recessive to the full color allele, codominant with the Siamese allele, and dominant to the blue- eyed albino and albino alleles, and produces an intermediate albinism, reducing the basic coat color from black/brown to a light beige with dark brown "points" in the classic Siamese pattern and producing bright blue eyes.
The Burmese and Siamese alleles are codominant, that is they each have exactly as much dominance or recessivity. It is possible to have one of each allele, "cbcs", producing a Siamese-patterned coat with a darker base body color and turquoise (aquamarine) eyes: the Tonkinese pattern.
The blue-eyed albino allele, "ca", is mutant, is recessive to the full color, Burmese and Siamese alleles and dominant to the albino allele, and produces a nearly complete albinism with a translucent white coat and very washed-out pale blue eyes.
The albino allele, "c", is mutant, is recessive to all others, and produces a complete albinism with a translucent white coat and pink eyes.
The albanism genes combine in some rather interesting ways:
C cb cs ca c C full color full color full color full color full color cb full color Burmese Tonkinese Burmese Burmese cs full color Tonkinese Siamese Siamese Siamese ca full color Burmese Siamese B-E Albino B-E Albino c full color Burmese Siamese B-E Albino Albino Notice how the dominance characteristics among the alleles are normal except for the combination of Burmese and Siamese, which produce the Tonikinese pattern.
The Agouti Gene The next gene controlling the pattern of the coat is the agouti gene. This gene will control ticking and comes in two alleles: agouti, "A", and non-agouti, "a".
The agouti allele, "A", is wild, is dominant, and produces a banded or ticked (agouti) hair, which in turn will produce a tabby coat pattern.
The non-agouti allele, "a", is mutant, is recessive, and suppresses ticking, which in turn will produce a solid-color coat. This gene only operates upon the color gene (black, dark brown, or light brown) in conjunction with the non-orange allele of the orange-making gene and is masked by the orange allele of the orange-making gene.
The Tabby Genes The last of the genes affecting the coat pattern is the tabby gene. This gene will control the actual coat pattern (striped, spotted, solid, etc.) and comes in three alleles: mackerel or striped tabby, "T", Abyssinian or all-agouti-tabby, "Ta", and blotched or classic tabby, "tb".
The mackerel-tabby allele, "T", is wild, is co-dominant with the spotted tabby and Abyssinian alleles and dominant to the classic-tabby allele, and produces a striped cat, with vertical non-agouti stripes on an agouti background. This is the most common of all patterns and is typical grassland camouflage, where shadows are long and strait.
A spotted tabby is genetically a striped tabby with the stripes broken up by polygene influence. There is no specific "spotted-tabby" gene. This spotted coat is a typical forest camouflage, where shadows are dappled by sunlight shining through the trees. Do not confuse the spots of our domestic cats with the rosettes of the true spotted cats: entirely different genes are involved.
The Abyssinian allele, "Ta", is mutant, is codominant to the mackerel- tabby allele and dominant to the classic-tabby allele, and will produce an all-agouti coat without stripes or spots. This all-agouti coat is a basic type of bare-ground camouflage, seen in the wild rabbit and many other animals.
A special case occurs when both the mackerel-tabby and Abyssinian alleles are expressed, "TTa". This will produce a unique coat consisting of the beige ground color with each hair tipped with the expressed color. By selective breeding, the ground color has become a soft gold, producing the beautiful golden chinchilla cats.
The blotched- or classic-tabby allele, "tb", is recessive to both the mackerel-tabby and the Abyssinian alleles and will produce irregular non-agouti blotches or "cinnamon-roll" sworls on an agouti background. When the "cinnamon-rolls" are clean and symmetrical, and nicely centered on the sides, a strikingly beautiful coat is achieved.
The "coat of choice" in Europe is the classic tabby (hence the name), probably because of the similarity in appearance of a large mackerel tabby domestic cat and the European Wildcat, the former being soft and cuddly and the latter prone to remove fingers. In the U.S., the reverse is true.
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