The Main Genes of Smokes
A = Agouti and is the ground-color of tabby; hairs banded yellow/orange.
a = Non-agouti and is hair that is not banded; unicolored (acts only on black/brown).
B = Black pigment
b = Brown (chocolate or chestnut) pigment.
C = full-color, or maximum pigmentation.
D = Dense pigmentation.
d = Dilute pigmentation (eg. black to blue)
I = Inhibitor gene. Suppression of pigmentation from parts of hairs.
i = Normal pigmentation. Full development of pigmentation.
O = Orange, or all pigment turned to yellow/orange.
o = Normal pigmentation (not orange).
The hairs in smoke persians are tipped with color. The depth of the tipping distinguishes a cat as either shell, shaded, or smoke. A Shell has the lightest tipping and is recognized by CFA in only two colors which are red (Shell Cameo)and tortoiseshell (Shell Tortie). The next darkest color is the Shaded group and agian only the reds and torties are recognized by CFA (Shaded Cameo and Shaded Tortie). The darkest in the group are the Smokes with most of the hair being colored. Smokes are recognised by CFA in all colors which include black, red, blue, cream, blue/cream, and tortie. Smokes are the most common coloring while the shadeds and shells more rare. They are also being bred with bi-colors to produce bi-colored smokes (bi-colors are those cats with the spotting gene that produce cats with patches of white such as the calico).
Genotypes of tipped colors
aaB-D-I- = Black Smoke
aaB-ddI- = Blue smoke
D-I-O(O) = Shell Cameo, Shaded Cameo, Smoke Cameo (Red Smoke)
ddI-OO = Cream Smoke Cameo
D-I-Oo = Shaded Tortoiseshell, Smoke Tortoiseshell
ddI-Oo = Dilute Smoke Tortiseshell (Blue/Cream Smoke)
As a note of comparison, the geneotype for a solid black cat is: aaB-C-D-. Note the only difference between a solid black cat and a black smoke is the I or Inhibitor and the C or Full color genes. The best-known smoke is the black, and it is due (as are all smokes) to the combined action of the Inhibitor gene and the non-agouti a. The I gene produces a white undercoat, but the a gene produces extra amounts of pigment. The result is profuse tipping, but modifiers can increase or decrease the tipping to the extent that some smokes are almost indistinguishable from solid colored cats and others are very pale. The long-haired smoke with just the right amount of tipping and undercoat is undoubtedly a magnificent cat.
The cameos are the red equivalent of black smokes. The result from combining the I gene witht he orange O. These too are beautiful cats, possessing a white undercoat and an overlay of rich apricot to red tipping.
There are three varieties in smokes, corresponding to the three degrees of tipping. The palest is the shell cameo which has a delicate sprinkling of red tipping. Next is the shaded cameo which has a slightly darker red appearance. Darkest is the smoke cameo in which the undercoat is white and the veiling is ideally a deep, even red. As with all red cats, however, tabby marking are inherent and can be dispersed only by selective breeding. This is because the non-agoutie gene is ineffective on orange pigment, and for this reason too the smoke cameo - unlike other smokes - owes its intensity of color only to polygenes and selective breeding, not to a non-agouti geneotype. When tabby markings are allowed to remain, the result is the cameo tabby, with red markings on a white background.
A very elegant series of cats are the blue smokes and cream cameos, produced by introducing the dilution gene d. These are clearly of smoke form, as shown by their white undercoat, but the tipping is now cream or blue. There is considerable variation in the cream tone, from warm cream to an exquisite pale shade that has the slightest hint of pink, due to the action of polygenes. You can also get a poor quality cream that has a flat "brown paper bag" look. This is why it is important to not only breed for "type" and personality, but breed for favorable color factors.
The dilute smokes are the least often bred colors because of the complicated color factors and most importantly, the difficulity most breeders have in determining whether a kitten is a smoke or a solid. The "clown" markings can be difficult to see because of the pale coat color (for more information on how to tell if you have a smoke or a solid kitten, see the page on determining factors).
The following chart is a basic guide for combining the red and black genes. When figuring for dilutes you must take that gene into consideration as well as any dilute carriers. Factor into that the smoke gene, and you can see just how complicated breeding smokes can be!
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