(Subtly copied from WR~)
As artists who are constantly changing around the designs of beloved and well established characters from a very nostalgic series, it's understandable that a few fans get ruffled by the changes... but we hope they understand and are more accepting when we explain exactly what we have done. ^^
Some of the most frequent comments we get are from fans who insist that a cat could have gotten a specific gene from a distant relative... which totally works, if the gene is recessive! But most commonly, it concerns dominant genes such as red and white.
What it all boils down to... simply, Erin had no idea what she was doing. She's even gone on record, saying she has absolutely no idea about cat genetics. Well, we do! And we're going to share the basics with you now:
¤ Solid Colours
Black, chocolate and cinnamon are all versions of the eumelanin genes, situated on the same alleles. A cat has two alleles per pair, aka the cat can carry at most two of these at once, which offspring can inherit. For example, Black/Cinnamon. Dominant traits are almost always expressed, while recessive traits need two carrier parents (at least) to be expressed.
Dominance: Black > Chocolate > Cinnamon (B > b1 > b2)
B/B – black cat
B/b1 – black cat
B/b2 – black cat
b1/b1 – chocolate cat
b1/b2 – chocolate cat
b2/b2 – cinnamon cat
Red is different, because it’s a phaomelanin gene, and it’s found on the sex chromosome X, meaning it’s connected with the cat’s gender in what way it’s expressed. It also makes it more dominant the the eumelanin colours.
Males have XY – if their X carries red, their whole pelt becomes red.
Females have XX – if both X’s carry red she too becomes a red cat. If only one X has red however, something called X-inactivation happens. That means all the cells in her body randomly decide which X they’ll use, giving rise to tortoiseshell patterns. The dense, coloured coat is called “brindled” in the absence of white spotting.
Dominance: Red > Black > Chocolate > Cinnamon (O > B > b1 > b2)
O/O – red cat
O/o – red-and-eumelanistic-colour colour cat
o/o – non-red cat
O/O – red female; she still carries other colour genes, but they will not be expressed
O/B – red-and-black tortie female
O/b1 – red-and-chocolate tortie female
O/b2 – red-and-cinnamon tortie female
(With the addition of tabby patterning tortoiseshells become tabby tortoiseshells, aka torbies)
O – Red male; he can still carry other colour genes, but they will not be expressed
A gene working with the pigment of the hairs through coding of the protein melanophilin. It deposits pigment into the hairs, deciding the intensity. It’s situated on two alleles, hence it has different ways of being expressed. Non-dilute colours are dominant, while diluted colours are recessive.
(D/D > D/d > d/d)
D/D – non-dilute colour only
D/d – expresses non-dilute colour, but carries dilution
d/d – diluted colour only
With the addition of dilution, all self-colours become diluted:
Black – Blue
Chocolate – Lilac
Cinnamon – Fawn
Red – Cream
A tortoiseshell cat will either be fully dilute, or fully non-dilute because the dilution gene works on both colours. Exceptions are chimeras (fused embryos).
¤ White spotting
White spotting, also called the piebald gene, masks all other colours.
Dominance: White spotting > Red > Black > Chocolate > Cinnamon (S > O > B > b1 > b2)
It’s a variable gene, which has several expressions.
S/S – between 50-100% white spotting
S/s – between 0-50% white spotting
s/s – no white spotting
An S/s cat can look solid, but genetically will still carry white and be able to have white spotted offspring. Such cats are usually found with at least a couple strands of white hair.
White fur is technically “colourless” fur, which when it spreads to the face, can give blue “colourless” eyes. Odd eyes often happen too.
White spotting also affects the tortoiseshell pattern.
Low white spotting – dense, brindled tortie pattern
High white spotting – patched, distinct tortie pattern in what appears to be a white base
Some cats who have a few strands of white hairs are not always white spotted cats, but can be injured cats. When suffering an injury, the hair sacs can be damaged, and will produce white hairs instead.
Old cats tend to become grey around the muzzle and face, and certain illnesses like vitiligo causes loss of hair pigment over a period of time.
¤ Dominant white
The white masking gene, unlike white spotting, completely masks the normal production of pigment cells. These cats may carry any colours, but appear white no matter what. It exists on a separate gene from other colours.
Dominance: Dominant white > White spotting > Red > Black > Chocolate > Cinnamon
(W > S > O > B > b1 > b2)
W/W – solid white cat
W/w – solid white cat, carrying gene for non-white
w/w – non-white coloured cat
Cats of this kind of white have the highest chance of being born deaf, by the exception of their eye colours. Blue is still the statistically the most common case for deafness, as is being odd-eyed, but there are many cases of both amber- and green-eyed dominant white cats being deaf.
Some of these kittens are born with a dark smudge on their brows that later on disappears.
¤ Tabby patterns
Beside the main pattern genes, there is a gene called agouti, which decides whether the cat is solid or tabby by signalling protein to cause certain pigmentations of the hair shafts. It is also a dominant gene, while its recessive form masks any patterns.
A/A – tabby cat
A/a – tabby cat that carries gene for solid
a/a – solid cat
The only exception is the red gene O, because it is dominant over a, hence all red cats, even if they are genetically solid, appear like tabbies.
The difference between a genetically-tabby and non-tabby red cat is its undercoat– a genetically solid red cat will not have the pale muzzle and underbelly that accompanies true tabbies.
Solid cats can, especially while they’re kittens, express a “ghost pattern” that fades.
There are many types of tabby, and many are modified cases where breeders work with several genes to give a certain look, hybrids, and random patterns in certain populations, and there is not always an established line of dominance.
Basic tabby patterns at least, are as follows: Spotted tabby (Sp), Mackerel tabby (Mc) and Classic tabby (mc).
Dominance: Ticked > Spotted > Mackerel > Classic (Ta > Sp > Mc > mc)
The ticking gene exists on a separate allele, and is a variable gene. A cat carrying two genes for ticking will appear almost solid, with dark bands of hair prominent on its forehead, legs, back and tail. A cat carrying only one gene for ticking will have banded hairs on its body, but will have stripes on its face, neck, tail and legs.
Keep in mind that the spotted tabby behaves in a different manner than breed-specific spotted cats, such as Savannahs and Bengals. It has been verified that spotted tabbies happen through the assistance of a separate gene which breaks up tabby markings. The Sp gene modifies both the mackerel and the classic tabby markings, but is hypostatic to ticking, hence it will be hidden when the Ta gene is present. A mackerel spotted tabby will have more vertically aligned spots than a classic spotted tabby.
Ta/Ta – ticked tabby cat
Ta/ta – ticked tabby cat, carrying non-ticking gene
Ta/ta – non-ticked cat
Sp/Sp - spotted tabby cat
Sp/sp - spotted tabby cat, carrying non-spotted gene
sp/sp - non-spotted tabby cat
Mc/Mc – mackerel tabby cat
Mc/mc – mackerel tabby cat, carrying gene for classic tabby
mc/mc – classic tabby cat
The gene C codes for tyrosinase, an enzyme which works on the early stages of pigment production. It is a dominant gene, but has a whole range of recessive variants, ranging from complete albinos, to the so-called temperature albinos. Temperature albino is the alternative word for colourpoint cats.
Dominance: Colour > Burmese colourpoint > Tonkinese colourpoint > Siamese colourpoint > blue-eyed albino > pink-eyed albino
(C > cb > cs > ca > c)
C/C – normal coloured cat
C/cb – normal coloured cat carrying Burmese colourpoint
C/cs – normal coloured cat carrying high contrast Siamese colourpoint
C/ca – normal coloured cat carrying blue-eyed albino gene
C/c – normal coloured cat carrying pink-eyed albino gene
cb/cb – Burmese colourpoint cat
cb/cs – Tonkinese colourpoint cat
cs/cs – less contrast Siamese colourpoint cat
cs/ca – high contrast Siamese colourpoint cat
ca/ca/ or ca/c – blue-eyed albino cat
c/c – pink-eyed albino cat
(The Tonkinese colourpoint pattern is caused by the other two colourpoint genes working together because of incomplete dominance)
The temperature albinos are actually affected by the climate they live in, and their body temperature, which is proven by their coat colours. All kittens are born white, but as they grow, their naturally-cooler extremities darken because the pigment enzyme is allowed to work there. Hence, old colourpoint cats often have very dark coats overall too, as older cats’ body temperatures sink.
(Cats living in the northern parts of the world also are darker)
“Lynx point” is the name for colourpointed tabbies – only the extremities will have stripes, including maybe a hint of it along the back.
¤ Silver inhibitor genes
Warning: research for the silver gene is still on-going, so much of this section is theoretical!
Inhibitor genes mean “hindering” other colour genes to be expressed in their natural way. Instead, it turns the base hairs a pale silver, giving a shiny effect to the fur. These genes, however, are about the hardest to make out, because it’s likely that a whole lot of genes are present for the different variants of shading. It’s a dominant pattern, and masks all self colours.
There are four basic patterns:
Chinchilla cats, the lightest type, where only the bare tip of the hairs still retain their original colour, whereas the rest is white/off-white. These cats are always genetically tabbies, never solids, as seen by their dark-rimmed pink noses.
Shaded cats, is the “middle” degree of shading, with half the hair covered in white, but the expression can vary greatly. These are also genetically tabbies, proven by the dark-rimmed pink nose. Commonly bred by the union of a silver tabby and a silver chinchilla.
Silver Tabby cats, the least amount of silver shading, with only a quarter part of the hair shaft being white. These are also, quite obviously, genetically tabbies, due to the very visible pattern, and again, the black-rimmed, pink nose.
Smoke cats, the least amount of silver shading, with only a quarter part of the hair shaft being white. These are however, always solid cats, and yet again the expression varies from very dark coats, to very pale ruffs, caused most likely by polygenetics.
Theoretical inhibitor genes:
I – silver inhibitor gene
i – non-silver
Inhibitor gene + non-agouti gene = Smoke cat
Inhibitor gene + agouti gene = Silver tabby, Chinchilla, and shaded cats. (The difference in the expression of these coats are made by all the different polygenes)
An additional gene, the Wide-band gene (which is likely a group of polygenes that codes together, but is currently referenced to as a single gene, which is by far easier to explain) is also an important part of the silver makeup. It is assumed to be a gene which decides how far the the inhibition gene reaches on the hair shaft.
Wb/Wb - Silver chinchilla
Wb/wb - Silver shaded (theoretically also some high-contrast smokes)
wb/wb - Silver tabby/silver smokes
Golden shadeds are still very obscure, and it is uncertain whether they come from another, more recessive silver gene, polygenes working together, or whether it is a combination of non-silver and wide-band genes which gives rise to the golden colour. Thus, we've decided not to address the gene presently, before we know more.
¤ Amber extension gene
Formerly thought to be an X colour because it was highly unknown, amber is a colour extension gene, which means it changes the base colour over time. It hails explicitly from the Norwegian Forest Cat, though similar mutations that may be related have been seen in other breeds, and controls the production of different coloured pigment. At an early age, black coloured fur begins to turn into a reddish-brown hue called amber. As of today, this only counts for black cats (B and diluted B), and no other colour gene. Since it does not modify the red gene, red will still dominate even over amber-coloured black cats, and tortoiseshell cats will be red-amber rather than red-black.
It is a recessive gene, meaning it’s only expressed when there are two alleles carrying the same gene.
E/E – normal black colour cat
E/e – normal black colour cat, carrying amber gene
e/e – amber coloured cat
Amber changes any form of black fur, both solid and tabby, and light amber is the diluted version. Both white genes still remain dominant to amber, as with normal blacks, so white-spotted ambers are possible. Silver shading and smoke on top is also possible.
Amber is also similar to how the red gene treats non-agouti cats, by giving even solid amber cats the impression of tabby striping. Proper amber tabbies will have pink nose leathers, while non-tabby ambers have dark nose leather, and the similarly dark paw-pads can differentiate them. Ambers will also vary greatly in their expressions, some looking like washed-out ginger cats, other like pale goldens with dark, desaturated striping, and more constrasted undercoats, for example.
¤ Fur length
Two genes decide the cat’s fur length, situated on the same alleles. Shorthaired fur is the dominant form, while longhaired fur is recessive. (L > l) Rare dominant longhaired mutations have been observed too, but this is the general rule.
L/L – shorthaired cat
L/l – shorthaired cat carrying gene for longhair
l/l – longhaired cat
For those who think these guides too easy, please keep in mind that we have simplified them not for those who are already experts of cat genetics, but so as to make them easy to read for those who are new to this. This list is not finished by any means, as we intend to expand on it at later dates (and update in case we find new information, of course) but we felt it prudent to add these genes at the start, since they feature the most in our project.
While these are facts, carefully researched in order to be as correct as possible, biology is not like math; it is not one linear path from which knowledge is learned, but a moving, branching tree that always evolves, makes changes, and mutates. Allow me to quote my biology teacher:
“The problem in biology, is that one must account for all the rules, and their exceptions.”
Written by AnnMY
and IycanrocPlease do not re-post or re-distribute without credit!
Dr. Bruce Fogle’s “The New Encyclopedia of the Cat”; www.goodreads.com/book/show/90…