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Copyright 2014, Sarah Hartwell
The ancestors of the domestic cat were nondescript black / brown striped tabbies. Over the centuries , mutation produced a wide array of colours based on 2 different pigments. Eumelanin gives the blacks, browns and blues while phaeomelanin gives the reds, fawns and creams. A few other genes give further variations on those colours such silvers, colourpoints and solids/selfs. Mutations continue to occur and unexpected colours also turn up due to inbreeding where recessive genes, hidden for generations, start showing up.
During the 1990s , some purebred Norwegian Forest Cats in Sweden produced chocolate /lilac and cinnamon /fawn offspring. However , those colours are not found in the purebred Norwegian Forest Cat gene pool. Had the gene pool become polluted by someone , perhaps generations ago, breeding their Norwegian Forest Cat to another breed? Was it a spontaneous mutation? Crossing of those cats with known chocolate and cinnamon colour cats of other breeds ruled out chocolate/lilac and cinnamon/fawn genes. These cats were a totally new colour, peculiar to the Norwegian Forest Cat gene pool and dubbed the "X Colours". They are now called Amber and Light Amber. The Amber effect is due to the extension gene (also called red factor ) which controls the production of red and black pigment . The dominant version of the gene produces normal black pigment in the coat while the recessive version produces red pigment. The name comes from the effect of black or brown pigment not being extended throughout the whole coat, but being restricted to the skin of the extremities and to the eyes (for example in bay horses ).
This Norwegian Forest Cat was bred by Yve Hamilton Bruce from a silver mackerel tabby female (imported from Denmark) and a classic red tabby and white male . The result was 1 silver tabbies and 2 silver tabbies with white. At just over 3 months old, this silver and white tabby male developed a large patch of bright red hair on his back which continued to spread . Eventually the whole fur will become amber. The effect of amber during the colour-change stage depends on the original colour - solid black or blue , bicolour or tabby. The cat pictured is not a typical amber as it has the silver gene so the amber effect is overlaid on silver.
A non-agouti amber Norwegian forest Cat resembles a silver tabby, but has a distinctive black nose and black paw-pads instead of the pink /reddish nose with black outlining found on conventional silver tabbies. The photo below shows a non-agouti amber. According to Rui Pacheco, although this cat is clearly non-agouti because of the black nose, he has the phenotype of a silver shaded. Rui's theory is that the amber gene invalidates the action on the non-agouti gene; wide-banding will further lighten the base colour giving a very pale cat with black nose and paws. Amber cats are basically black cats with a colour modifier that affects the deposition of pigment on the hair shaft, but not the skin colour. That is why in non-agouti cats the nose remains black and in agouti cats it remains pink.
The platinum effect is found in some lines of Silver Persian/Chinchilla Longhair. In 1986/7, Cheryl Bennett reported in The Silver and Golden Persian Newsletter (ACFA) that one of her shaded silver females (Kelley Lane Contessa of WeANDE) had changed from pure silver to pale golden. Contessa’s parents were a shaded golden and a shaded silver; these were full siblings. At 10 – 12 months of age, Contessa began to “tarnish” i.e. show cream /reddish patches and by 3 years of age she was entirely pale golden. She produced a number of Silver Persians without tarnish, but she failed to produce any offspring when mated to a golden sire . One of Contessa’s male offspring turned from silver to golden as an adult . An adult Silver Persian from England (Lynchard Silver Shadow) was exported to Australia and also turned golden. Shadow had a few golden hairs on his paw, but did not turn golden until he was a year old when his coat turned to pale beige. By 3 years old he was entirely pale golden. Shadow was bred to a genetically golden female, but the pairing only produced silver offspring. However, at least one of his silver offspring later turned pale golden. Other descendents of Contessa also went through the late colour change. During the 1980s, several other breeders of Shaded Silver and Chinchilla Persians came forward to report that their cats had developed reddish, brownish or golden-coloured fur along their spines as they aged . Many of the cats had no golden in their ancestry. At first it was dismissed as an unavoidable genetic fault where silver was incompletely dominant and did not hide the recessive golden colour.
A common ancestor of all the colour- changing Silver Persians was a stud cat called Kelly Lane Andromeda (in the UK) whose descendents were exported to the USA in the 1950s and 1960s . Some of those descendents were influential stud cats and would have spread the mutant gene far and wide. Controlled inbreeding (linebreeding) helped establish the gene, which would later double up to produce colour-changing Silver Persians. The effect of this gene on Golden Persians, if indeed it has any effect, is not known.
Except for red-silvers and cream-silvers, silver cats should entirely lack phaeomelanin (red or cream pigment) and only have eumelanin (black, brown, blue etc) present . Perhaps some other gene causes the eumelanin structure to change so that it is perceived as a golden colour. Chemical analysis proved that the late colour change Silver Persians did not have phaeomelanin pigment present.
An amber-type effect has also been seen in a Manx cat. Janet McArthur bred a male Manx (a longy i.e. with tail ) that was born an ordinary black/brown mackerel tabby without much rufousing, as was his sister . In addition , the male had white ticking at the tips of his hair. As the male grew, his stripes faded out and became spots while the black markings also changed from black to a burnt red-brown colour and his white ticking became smaller. The change from stripe to spots was probably an optical effect caused by the change from black to red-brown. His dorsal line became a burnt golden brown, and the background colour was similar to a washed out sorrel colour (sorrel is a colour found in Abyssinians).
There are a few oddities in his ancestry. His mother , Pearl , was a black Manx and his sire was a normal black/brown tabby from the same black Manx mother. The inbreeding was accidental , and may have brought out a recessive gene. Pearl was born to a black/red tortie (carrying dilute and colourpoint) and a red van-pattern sire; this pairing should not produce solid black females so, barring an anomaly in her sire's germ line, Pearl may be a tortie where the red has not been expressed in the coat. Pearl has also produced a kitten that changed from black with white ticking at the hair-tips, to black smoke and then to solid black without ticking.
The informal term "bimetallic" (referring to a mix of silver and golden or silver-gilt) describes some Siberian silver tabbies that turn golden in a rather patchy fashion. Unlike the amber gene, the colour change does not start on the back and work downwards, but seems distributed throughout the coat. The formal name "sunshine" has been proposed for this emerging gene.
Similar to amber is russet, which turned up in a line of seal (brown) European-style Burmese in New Zealand in 2007. It has subsequently occurred found in the related Mandalay (similar to the Asian in Europe ) and appears to be a mutation of the extension gene. The first known russet was a pure-bred Burmese called “Molly” in 2007. There is now an experimental programme in NZ to breed Russet Burmese and to investigate dilute russet, russet tabby and solid russet (as opposed to the Burmese sepia form of russet).
The first russet kitten “Molly” was born an "odd-coloured lilac (lavender)" which gradually lightened as she grew, progressing through lilac-caramel and chocolate ticked tabby and then dramatically changing to red. Chocolate ticked tabby and red were both impossible from her pedigree, and in any case , reds are not born as chocolate tabbies! Several more unusually coloured kittens were born in different litters and all went through the same colour/pattern changes . The ancestors of these kittens were seal Burmese and had no silver, tabby or Mandalay (Asian) blood . The pedigree had both dilute and chocolate, there were no reds, creams or torties until 4 generations back. DNA testing showed some kittens to be genetically seal and other genetically chocolate. Hence the new colour is due to a different mutation currently known as russet. Russet appears to be due to a recessive mutation that causes black pigment (eumelanin) to gradually fade to a minimal amount while leaving red pigment (phaeomelanin)unaffected.
Russet kittens resemble tabbies at birth , but have pink noses and paw-pads, pale fur around the pads and genitalia and a pale tail-tip - all of which would be dark in tabbies. The muzzle and fur around the eye is ivory. The back is solidly dark rather than ticked, becoming pale ivory halfway down the flanks. The back becomes more ticked appearance, almost a saddle, as kittens undergo the colour change and the face becomes reddish. By age two, they may resemble a red Burmese. It differs from amber as ambers have dark noses and paw-pads. Non-agouti (solid) amber kittens are very dark with a dark face that is last to go red while russet kittens have off-white faces (possible due to Burmese sepia gene in the mix), which are the first part to go red (rather than the last as in ambers), and pale undersides. The russet colour change appears to be slower than the amber colour change. Russet kittens to date have been larger at birth than their siblings and somewhat on the large side as adults.
Copyright 2010 Sarah Hartwell
This page pulls together what is known about Don Shaw 's Barrington Brown gene, a form of recessive brown/colour dilution only reliably recorded in a colony of laboratory cats, none of which are believed to have left the laboratory. To make this comprehensible to the non-genetics expert I have referred to "copies of genes" or "versions" of genes although the correct terminology is "alleles". There is also a brief guide to Shaw's terminology at the end as Shaw's writing pre-dated modern "standard" symbols and terminology.
Don Shaw was an early feline geneticist in the USA. During the 1950s and 1960s, there was no standard form of genetic coding and Shaw used his own system of genetic coding which can be difficult to read today . He also referred to chocolate, which is a mutation of the black gene, as "chocolate dilution". What modern fanciers call dilution, Shaw called "maltesing" (Maltese i.e. blue cats were a genuine dilution of black). Shaw viewed dilution as being due to the reducing amount of melanin present in the hair and not by the way pigment forms clumps in the hair. Chocolate had less melanin than black, therefore Shaw called this dilution. Blue has a the same amount of melanin, but arranged differently, so Shaw did not consider this dilution.
In simple terms , the black (eumelanin) colours in cats is due to a series of genes (alleles to be precise) with the following order of dominance/recessive (most dominant at the top, most recessive at the bottom ). The chart also shows how these combine with dilution genes and dilution modifier genes. A cat inherits 2 copies of the black gene and only the more dominant version will show up while the recessive gene will be hidden. The caramel form only shows up in cats that already have the dilute colour and it lightens and adds a brownish cast to the dilute colour.
Caramel (UK: Blue-based caramel)
Lavender (Lilac)
Taupe (UK: Lilac-based caramel)
UK: Fawn-based Caramel
These colours will naturally look a little different on Burmese (due to the sepia gene), Tonkinese ( mink gene) and cats with the silver Inhibitor gene. For clarity, this article will ignore those additional genes and just look at the eumelanin (black) series of colours.
An additional type of recessively carried brown colour has been reported in laboratory cats, but not in the outside world. Termed "Barrington Brown", a cat with two copies of this gene had black pigment diluted as shown below. Because it hasn't (yet) been seen in the cat fancy , this gene is enigmatic to many fanciers.
Some have suggested it is the same as caramel (dilute modifier), however some reports indicate cats with 2 copies of the Barrington Brown gene were different in colour from cats with only one copy of the gene (which seems odd since the gene is recessive and cats with only one copy should have dilution at all). When 2 copies were present, Barrington Brown had an additive effect on black and chocolate, and presumably on cinnamon (which may have been unfamiliar to Shaw).
Deep mahogany brown
Light brown
Cafe -au- lait ( milk coffee colour)
The dilution only happens if 2 copies of Barrington Brown are present, although some sources suggest the genes had additive effect on each other to create the pale milk coffee coloured cats when there were 2 Barrington Brown genes. Since Barrington Brown is a recessive gene. If only one copy was present it should be masked by the dominant non-Barrington copy. This is part of the problem when interpreting reports that use an old, non-standard genetics notation!
ba - Barrington Brown Locus (unverified)
Homozygous - Non Barrington Brown
Cat unaffected - i.e. Black/Brown/Chocolate etc
Heterozygous - Non Barrington Brown - carrying Barrington Brown
Cat unaffected - i.e. Black/Brown/Chocolate etc
Homozygous - Barrington Brown - liberty of renaming
Mahogany Brown/Light Brown/milk coffee in colour (depending on whether cat is black/chocolate/cinnamon)
In the 1960s, chocolate was described as a dilution of black and the third possible version of the gene, cinnamon, was apparently unfamiliar to Shaw (or not reflected in his terminology). Shaw’s Barrington Brown article was first written in the 1960’s in the Journal of Cat Genetics, and reprinted in the early 1970’s in Cats Magazine and has been subject to much reinterpretation, especially when a dilute modifier emerged in the cat fancy.
According to Shaw's breeding data, Barrington Brown (mahogany brown) dilution was inherited in much the same way as “standard chocolate dilution" (black/chocolate alleles) by reducing the amount of pigment in the hair and by producing elliptical pigment granules instead of round granules. Elliptical pigment granules refract light differently and give a reddish-brown colour instead of black/sepia. In Shaw's terminology which can confuse modern readers, chocolate is a dilute of black (while blue is "maltesing" of black).
It became apparent that Barrington dilution gene was in a different location to the ordinary black/chocolate genes and was inherited independently of black/chocolate. That means it wasn't the modern cinnamon. Genes in different locations can affect different enzymes involved in production of the same protein, in this case the production of eumelanin pigment. Shaw referred to the “standard chocolate dilution" as affecting enzyme D while the Barrington system affected enzyme B. He identified Barrington Brown as having 2 alleles; the dominant wild type and the recessive Barrington Brown dilution.
B+ = Wild type gene. Apparently responsible for normal Enzyme B production, giving full intensity of melanin.
b = Barrington Brown recessive gene. When 2 copies are present there is less Enzyme B produced which means less melanin produced; the pigment granules are elliptical (reddish-brown) instead of round (black).
He gave it the name Barrington Dilution or Barrington Brown because it was discovered at the Quaker Oats Nutritional Laboratories in Barrington, Illinois. The first cat known to be homozygous for Barrington Brown was born at the Barrington Laboratories. This was a strangely colored light brown ( rich caramel or perhaps cafe-au-lait) male kitten homozygous for Barrington Brown as well as having “standard chocolate dilution". The 2 gene systems were additive in nature and each expresses its effect as if the other were not present i.e. the end result is the sum of both Barrington Brown and "standard chocolate dilution" being expressed. Shaw's description of "rich caramel" (light tan) misled 1970s breeders to believe the emerging dilute modifier was the same as Barrington Brown.
Don Shaw and Wayne Durdle investigated this gene in depth. Cats carrying the Barrington gene were donated by the Quaker Oats Nutritional Laboratory to the Feline Research Laboratory at Tuskegee Institute, Alabama (maintained there from summer 1966 to mid-1969). No Barrington Brown carriers were believed to exist outside of the colonies and Barrington and Tuskegee. Studies established that the light tan or cafe-au-lait colouration was due to the combined effects of "standard chocolate dilution" and their Barrington Brown gene.
Shaw had left the project in July 1968 and Durdle reportedly terminated the colony in June 1969 (this suggests the cats were destroyed, neutered or used in other research). To their knowledge - and to the ongoing chagrin of many breeders - the Barrington Brown cats had no direct descendents in the cat fancy and the gene was lost . However, Shaw noted that some "doubly diluted" kittens were appearing in the cat fancy. These had no apparent connection to the Barrington or Tuskegee cats. He also mentioned unconfirmed reports of a dilution system similar to the “standard chocolate dilution" but not traceable to any known chocolate ancestry.
Shaw offered the following possibilities:
  • a leak of the Barrington Brown gene from one or other of the laboratory colonies into the cat fancy population; perhaps some cats or kittens had been taken home as pets and bred.
  • a new mutation in a completely different gene location
  • a new mutation at the same location as his Barrington Brown gene
  • an independent recurrence of the Barrington Brown mutation.

To identify the relationship , if any between the Barrington Brown cats and those with "double dilution" would require test-matings between the new "doubly diluted" cats and some known Barrington Brown cats. Since there were no known Barrington Brown cats outside of the laboratory and the lab colony had been terminated, this wasn't possible. In the 1970s, Pat Turner stated , without any supporting evidence , that caramel (the double dilution mentioned by Shaw) was the same as Barrington Brown. The dilute modifier (caramel) colours are not the same as the colours described by Shaw, though some websites continue to repeat Turner's claim that Shaw called the caramel colour Barrington Brown. Turner had simply jumped to conclusions. Barrington Brown cannot be the same as caramel because Barrington Brown affected black and chocolate, but caramel only affects blue, lilac and cream.
Shaw noted that recessive traits emerge in pedigree cats because of line-breeding and inbreeding which matches together genetically similar individuals. This means a better chance of cats inheriting 2 recessive versions of a gene and new traits showing up as result - just as they did in the Barrington colony of cats.
From a breeder viewpoint, it is sad that "recessive brown" has been lost. Shaw's descriptions indicate that it wasn't the same as caramel. Its effects on the wider palette of feline colours - torties, ticked and patterned tabbies, Burmese sepias, minks and colourpoints - can only be hypothesised. From time to time there are reports of odd colours in cats, including a tantalising "palomino" described as "the colour of a brown paper grocery bag" from the USA that might just have been the light tan noted by Shaw.
Modern feline geneticists use b/b for chocolate, but Shaw defined chocolate as d/d, because to him it was a dilution of black. Reading Shaw's work on black, chocolate and Barrington Brown without knowing his terminology is therefore confusing. In Shaw's defence, the standard gene symbols had not been defined in the 1950s and 1960s.
Light tan/cafe-au-lait in Shaw's terminology is d/d, b/b. To a modern reader, d/d, b/b indicates lilac. This, as much as any visual similarity, helps explain why his Barrington Brown is so often confused with the dilute modifier.
Shaw’s Chocolate alleles
D+- = Normal colour (black/sepia)
d/d = chocolate (in Shaw’ s words , Chocolate Dilution)
Shaw’s Maltese alleles
M+ = Dense colours e.g. black
m/m = Maltese (or in our terms dilution) e.g. blue is the maltese of black
Shaw's Barrington Brown allele
B+ = Normal coat
b/b = Barrington Brown
Lilac (in Shaw's terminology) would be d/d, m/m = Dilution allele (chocolate) + Maltese allele = lilac. 
Lilac in modern terminology is b/b, d/d = Chocolate allele + dilution allele = lilac.
Although there is no official modern symbol for the lost Barrington Brown, Ba is often used for convenience in modern discussion (since it isn't allocated to anything else ).
Brown Locus (modern symbols)
B/- = Black/Brown (Shaw's black/sepia)
b/b = chocolate (Shaw's "standard chocolate dilution")
bI/bl = cinnamon (probably not recognised by Shaw)
Barrington Brown Locus (modern symbols)
Ba/Ba - no Barrington Brown dilution
ba/ba - Barrington Brown dilution/recessive brown
Copyright 2002 - 2013 Sarah Hartwell
Genetically speaking, there are four basic self (or solid) colours of cats: black, chocolate, cinnamon and red. All other self colours are modifications of these. Although covered here as a self colour, red is a form of tabby and it is impossible to completely eliminate the tabby markings. Why are there not five basic colours? White is counted as an absence of colour rather than a colour.
Different countries, registries and breeds have different names for some of the same basic colours. Even where the same name is used, there may be different views on what is an acceptable or ideal version of that colour. Colours which appear identical to the human eye are caused by different genetic interactions.
The same colours are called by different names in different breeds. Even in the same breed, the colour may have different names depending on which country the cat comes from and which registry it is registered with. American registries like to add "mink" after the Tonkinese colours whereas British registries use the same name for that colour as is used in the equivalent Siamese or Burmese colour. Confused? Don't worry - there are some cross - reference tables later on!
The jet-black colour you known as "black" is called " ebony " and "ebony tabby" in Orientals, "black" in solid coloured domestic shorthairs, "brown" when it refers to brown tabby domestic shorthairs, "bronze" in Egyptian Maus, "tawny" in Ocicats and "ruddy" in Abyssinians. In colour-pointed cats, "black" is called "seal". In Burmese it is " sable " or "seal sepia" and in American Tonkinese it is "cinnamon" or "natural mink". In the Asian breed (self Burmese cats) it has a breed name to itself "Bombay". Shaded silvers, black smokes and chinchilla cats may look various shades of grey or silver, but they are black cats with silver roots to their fur. Add dilution and it becomes "blue". Modify the dilution and it becomes "caramel". Yet it is still basically a black cat.
Strange as it may seem , all red cats are actually red tabby because the non-agouti gene (the gene that turns a tabby into a self/solid colour) does not affect the way red pigment is deposited. A variety of other genes, called polygenes or modifiers, control the intensity of colour and contrast between markings and background colour. Selective breeding has reduced the tabby markings to produce a cat that looks solid red by breeding from those cats with the least red markings (cats with "low contrast" between markings and background colour). Because the non-agouti gene does not work on the red pigment, red tabby ghost markings can never be completely eliminated and may be seen on the tail, legs and forehead and as a darker region along the spine . Even though red cats are registered as "red self" they are still red tabbies, albeit red tabbies with very reduced markings. Because they lack the polygenes for high contrast between markings and background colour, their offspring also appear to be red self. More information can be found in Robinson 's "Genetics for Cat Breeders".
The simplest modification of the 4 basic colours is dilution. As the name suggests, this "washes out" the original colour to something paler. This is also called maltesing since the it was first identified in black cats and blue cats - Maltese is term for blue-grey and some of the eary blue cats imported into Britain were known as Maltese cats.
A secondary type of dilution is called the dilute modifier. It only affects already diluted colours. Since it gave rise to the colour "caramel". I have referred to it here as "caramelising" purely to avoid confusing the layperson. Textbooks always refer to it as the dilute modifier.
Caramel (UK: Blue-based caramel)
Lavender (Lilac)
Taupe (UK: Lilac-based caramel)
UK: Fawn-based Caramel
Light Amber
Black, chocolate and cinnamon are all versions of the same gene. With the exception of "red" which is a special case, genes are inherited in pairs - one from each parent . Some genes are dominant over others and only the dominant one will be expressed (show up). The other gene (the recessive) will still be lurking in the background and can be passed on to offspring. Depending on which pairing a cat inherits, it will be one of those basic colours. The fact that at it may look different depends on many other genes which alter the way in which these three basic colours are expressed.
If it inherits black + black OR black + chocolate OR black + cinnamon it will be black.
If it inherits the dilution gene it will be blue.
If it inherits the dilution gene AND the caramelising gene it will be caramel.
If it inherits chocolate + chocolate OR chocolate + cinnamon it will be chocolate.
If it inherits the dilution gene it will be lavender.
If it inherits the dilution gene AND the caramelising gene it will be taupe.
If it inherits cinnamon + cinnamon it will be cinnamon in colour.
If it inherits the dilution gene it will be fawn.
If it inherits the dilution gene AND the caramelising gene it will be a pink-brown..
Many early caramels were probably registered as fawns or lilacs, probably as poor quality individuals. The colour differences are subtle enough that it may be necessary to check what is in a cat's pedigree to work out the exact colour. To the rest of us, such cats are simply "biscuit colour" and are no less attractive for it!
Red is a different gene to black, chocolate and cinnamon. It is a sex- linked gene which means a female must inherit 2 copies of the red gene in order to show up as a red cat. A male only needs one copy of the red gene to be a red cat. This is why ginger tomcats are more common than ginger females (though contrary to popular belief , ginger females are neither rare nor infertile!). If a female only inherits one red gene, she is a tortoiseshell.
If a female inherits red + red she will be red (ginger).
If she inherits 1 red gene she will be tortoiseshell (red/black, red/chocolate or red/cinnamon depending on the other genes present)
If she inherits red + red AND the dilution gene she will be cream.
If she inherits 1 red gene AND dilution gene she will be dilute tortoiseshell (blue/cream, lilac/cream or fawn/cream)
If she inherits red + red AND the dilution AND the caramelising gene she will be apricot.
If she inherits 1 red gene AND dilution gene AND the caramelising gene she will be dilute tortoiseshell in the caramelised range of colours (though this may not show up very well and may be impossible to identify.)
If a male inherits 1 red gene he will be red.
If he inherits 1 red gene AND dilution gene he will be cream.
If he inherits 1 red gene AND dilution gene AND caramelising gene he will be apricot.
In reds, there are genes for rufism i.e. for the depth of the red colour. This is why show-quality reds are a rich, deep red colour while alley cats are more often marmalade or ginger. Early reds (1880s) were known as yellows; the depth of colour was improved over many generations of selective breeding.
In 1924, a series of breeding experiments between a Siamese female and a tabby male resulted in black offspring that themselves produced tabby offspring. This suggests a gene for black that is dominant to tabby, the opposite of the known behaviour of tabby and black! It is possible that the Siamese female, one of a pair imported from Bangkok , had a mutation for black colour that was dominant instead of recessive. There have been no further reports of dominant black in the cat population. Dominant black is genetically different to the black colour described above , but unless it occurs again its interaction with other genes will remain unknown.
Note : The usual explanation of black (B), brown/chocolate (b) and cinnamon (bl) is that there are 3 alleles of the black locus gene. Chocolate carrying cinnamon can appear as light chocolate in some breeds, but basically there are 3 phenotypes: black, brown/chocolate and cinnamon. An alternative explanation suggests 2 gene loci, each with two alleles. One locus is black/brown. The other locus is a modifer that, when homozygous (2 copies are present), changes black to cinnamon and brown to pale cinnamon. This gives 4 phenotypes: black, brown/chocolate, dark cinnamon/light chocolate and light cinnamon.
An additional type of recessively carried brown colour was reported in laboratory cats in the USA in the 1960s, but not in the outside world. Termed "Barrington Brown", a cat with two copies of this gene has black diluted to deep mahogany brown, chocolate dilutes to light brown and cinnamon dilutes to a pale cafe-au-lait. There are suggestions it may have been the caramel gene, but the descriptions of the colours quite different. The confusion seems to stem from the discovering describing the light tan of the Barrington Brown cats as "caramel coloured". Barrington Brown cannot be the same as caramel because Barrington Brown affected black and chocolate, but caramel only affects blue, lilac and cream.
The Dilute Modifier gene was posited by Patricia Turner who erroneously believed it to be the same as the Barrington Brown gene reported in a colony of laboratory cats. In essence, caramel lightens and gives a brownish cast to the underlying colour. How can adding brown make something lighter? Brown (in terms of colour, not genetics) comes in a variety of shades ranging from fawn to chocolate and adding a brownish hue is not the same as mixing paint . With the dilute modifier, blue becomes caramel, lilac becomes taupe (brownish grey) and red becomes apricot. In practice , these colours may only be visually distinguishable from each other by knowing the cat's genetics. Some find caramel cats resemble golden series cats and suggest that a theoretical hypostatic (hidden) silver/golden gene is showing through, especially in the lighter colours where there is nothing to mask a hidden silver/golden colour.
In the past, the Dilute Modifier has also been called “double dilution” and “caramelising”. Some people are still not convinced about caramel because almost identical colours can result from blue + caramel and from lavender/lilac + caramel. With a modifier gene, it is possible to get the same end colour (visually) from 2 different base colours (genetically). It depends on what the Dm gene is modifying (the expression of a protein) which is different from mixing paint. Two different original proteins (relating to melanin production or deposition) could be modified by such a gene to produce almost identical expression.
The Extension gene (formerly the Black Modifier gene) brightens black areas of the coat. At birth, kittens appear to be black or blue (it has not been found in combination with other genes recessive to black), but become brighter as they grow. The Black Modifier has so far only been observed in the Norwegian Forest Cat. Recognition of the colour by registries will allow the cats to be correctly registered and distinguish them from chocolate, lilac, cinnamon and fawn (not found in Norwegian Forest Cats).
Light Amber
During the 1990s, some purebred Norwegian Forest Cats in Sweden produced chocolate/lilac and cinnamon/fawn offspring. Because these colours are not recognised (they indicate outcrossing) they were called "x-colours". Crossing a "cinnamon spotted" x-colour with a fawn Somali produced blacks and blues, not fawns. Some x-colour cats were registered as "golden", but the x-colour can be found in combination with silver (x-colour silver tabbies), ruling out golden: a cat can be either silver or golden, but not both. The offspring of an x-colour "cinnamon spotted" and a chocolate point Birman were black and blue tabbies, ruling out the recessive chocolate, lilac, cinnamon or fawn and ruling out a recessive masking factor (i.e. that found in colourpoint cats). To produce black and blue offspring, the x-colour must be genetically black (dominant to chocolate). Further test-matings upheld these conclusions.
Self (solid) x-colour cats were born as poorly coloured black-silver or blue-silver tabbies. Their tabby ghost-markings faded as they matured and the colour became bright apricot to cinnamon colour with dark brown paw pads and nose leather with no black rim (a black rim is characteristic of silvers). Mating a self x-colour cat to a black-and-white and mating two self x-coloured cats together showed that the colours were not agouti (not ticked), but were new colours, now called Amber and Light Amber. Kittens are born dark and undergo a period of extreme brightening of the black/blue areas as they mature. Their original birth colour is often seen only on the back and tail, allowing amber and light amber to be distinguished from one another.
Amber is apricot-to-cinnamon colour with brown paw pads, nose leather and eye rims. Kittens are born dark or black, with ghost markings, and brighten as they mature. Light Amber is a pale beige colour. Kittens are born blue and brighten with age, becoming pink-beige to fawn at maturity. The nose leather, eye rims and paw pads are dark blue grey. (To complete the description of amber/light amber: Amber Tabbies are born apricot with black markings; the markings brighten to reddish-brown/cinnamon at maturity. The nose is pink and the paw pads and eye rims are brown. Light Amber Tabbies are born beige with blue tabby markings; the markings brighten to pink-beige/fawn at maturity. The nose is pink and the eye rims and paw pads are blue-grey. Amber/light amber replaces black/blue in torties. Amber also occurs with silver and in bicolours/tabbies -and-white.)
The provisionally named Russet Burmese is an experimental Burmese colour in New Zealand. In 2007, Nicki and Bob Mackenzie's line of seal (brown) Burmese (carrying dilute and chocolate) produced "odd-coloured lilac" kittens which gradually lightened as they grew, progressing through chocolate ticked tabby to red. The kittens traced to the same father and two related females (mother and daughter ) and all three shared a common ancestress only a few generations back. DNA testing showed the russet kittens to have the standard seal or standard chocolate genes, meaning there is an a different gene causing the colour change. Russet kittens also tended to be larger than their littermates, both at birth and as adults. Russet appears to be a recessive gene from a spontaneous mutation. It causes the black pigment (eumelanin) to gradually fade to almost nothing while leaving the red pigment (phaeomelanin) unaffected. Like the amber colour change, it might be an extension gene mutation.
Russet kittens have pink noses and paw-pads and a pale tail-tip. The muzzle and fur aroundthe eye is ivory. The back is solidly dark rather than ticked, becoming pale ivory halfway down the flanks. The back becomes more ticked appearance as kittens undergo the colour change and the face becomes reddish. By age two, they may resemble a red Burmese. It differes from amber (in Norwegian forest Cats) as ambers have dark noses and paw-pads. Non-agouti (solid) amber kittens are very dark with a dark face that is last to go red while russet kittens have off-white faces (possible due to Burmese sepia gene in the mix), which are the first part to go red, and pale undersides. The russet colour change appears to be slower than the amber colour change.
The type of dilution seen in cats is blue dilution (it dilutes black to blue). A second type of dilution seen in many mammals is "pink-eyed dilution". Pink-eyed dilution is characterised by a pink or ruby glimmer to the eye (depigmentation). The coat colour is often diluted to bluish-fawn and the pink-eyed dilution factor is generally inherited as a recessive gene. A possible pink-eyed dilute female cat was reported in 1961. She was described as pink-eyed with a light tan coat. She was mated to a chocolate point Siamese and produced three tabby kittens 10 days premature. Sadly none of the kittens survived. The colour of the kittens implies that pink-eyed dilution in cats is inherited as a recessive trait and is independent of the colourpoint genes. The pigment granules in the hairs of pink-eyed dilute cats were very small and yellowish brown,instead of the normal dark-brown or black. ( Todd NB: A pink-eyed dilution in the cat. JHered 52:202, 1961.27.)
Albino is generally thought of as pure white, but the situation in cats is more complex . There are five known alleles for albinism : blue-eyed albino, pink-eyed albino, Burmese pattern, Siamese pattern and full colour (non-albino). Full colour is dominant to all of the other four alleles. Burmese pattern is incompletely dominant to Siamese pattern; cats that inherit one of each of those genes will be intermediate in pattern and is known as Tonkinese. A quirk of the Siamese form of albinism is that it is temperature dependent with warm areas of the body being paler than cooler areas. For this reason , it is often described as "colour restriction" rather than albinism. Pink-eyed albino appears to be recessive to all of the other albino mutations.
The albino cat reported in Europe and the USA seems to be intermediate between pink-eyed albino and blue-eyed albino. Although it has the white coat of a true albino, its eyes have ruby red pupils and pale blue irises. A true pink-eyed albino was reported in 1931 and again in 1980s in the USA. Albino kittens have turned up more recently in the Bengal breed, unsurprising since albinism is found in the Asian Leopard Cat (the wild parent of the Bengal).
Dominant white is the colour associated with deafness in cats. Dominant white masks all other colours and cats may have blue, orange or odd eyes. Those with blue eyes have a high chance of deafness. Those with one blue eye have a high chance of deafness on the blue-eyed side. Those with orange eyes are far less likely to be deaf . Some dominant white kittens are born with smudges of coloured fur on top of the head, this smudge of colour usually disappears by adulthood, but kittens with colour smudges are more likely to have normal hearing.
The gene for white spotting can also create the impression of a self white cat. This gene is semi-dominant and is variable in the way it is expressed - a cat may have no visible white spots or may be wholly white and all stages in between those two extremes. Unlike dominant white, white spotting is not linked to deafness.
Another form of modification is colour restriction. This is seen in colourpointed cats where the colour is restricted to the head, tail and legs ( plus scrotum in males ). This is a form of partial albinism. As well as restricting where the colour will be exhibited, it tends to "bleach out" the colour to a greater or lesser degree depending on the type of colour restriction. It may seem odd to think of these as solid colour cats, but genetically they are; they have just had a "special effect" overlaid on them.
There are three colour-restriction patterns :
In the Siamese (Himalayan) pattern, there is maximum contrast between the points and the body colour.
In the Burmese, there is the least contrast but just enough to be able to see that the cat is not a single solid colour.
In the "Mink" Tonkinese, the effect is moderate.
The self colours may have different names in these cats. Alternatively a colour which appears identical to one of the solid colours may be genetically different because of the mild to moderate bleaching effect. A seal-point Siamese may appear to be brown, but genetically it is black!
In Abyssinian and Somali cats, the agouti gene causes the colour to be distributed in bands along each hair. This creates a ticked effect. The most confusing aspect is "red". The bright red colour in sorrel Abyssinians is really cinnamon. The dark red of the Usual Abyssinian is genetically black. Where registries recognise the sex-linked red and sex-linked cream colours the colour name is prefixed by the words "sex-linked". In the USA, the sex-linked colours are apparently not recognised to avoid confusion with the sorrel and fawn colours. To the naked eye (or without the benefit of a pedigree chart), the colours are practically indistinguishable.
It has been thought there were 2 different shades of sorrel red: a bright coppery red and a dark red characterised by an influential American Abyssinian sire called Champion Dhmahl's Diablo. Some pale kittens darken to red, while others become deep solid- looking red with minimum ticking. The dark red is more likely to be chocolate. Chocolate and lilac, along with the silver series, are considered alien to many North American breeders, but are familiar in Europe.
Full Expression
Sepia (Burmese)
Mink (Tonkinese)
Pointed (Siamese)
Australian Mist
Black/Brown (in tabbies)/Ebony
Brown/Sable/Seal Sepia
Sable/Natural Mink
Blue/Blue Sepia
Chocolate/ Chestnut/Brown
Chocolate/ Champagne Sepia
Chocolate/ Champagne Mink
Lilac/Lavender/ Frost
Lilac/Platinum Sepia
Lilac/Platinum Mink
Cinnamon/Cinnamon Sepia
Cinnamon/ Honey Mink
Fawn/Light Lilac
Fawn/Fawn Sepia
Fawn/Beige/Dilute Sorrel (non sex-linked)
Red/Red Sepia
Sex-linked red
Cream/Cream Sepia
Sex-linked cream
The colour can also be restricted to the ends of each hair. This is caused by a gene for silver. Chinchilla ( shell ) is the lightest form of tipping or shading - hair tip is coloured and hair shaft is silver, giving a sparkling appearance. Shaded is the next degree - the colour extends further along the hair shaft, darkest on the back (where fur is longer) to create a mantle of shading. Smoke is the heaviest tipping - the undercoat colour is reduced to a small band near the hair root so that the cat appears to be solid colour with a pale ruff until the coat is parted and you can see the silver roots. In goldens, the effect is similar except that the hair shaft is gold rather than white. These cats are still self colours, but the colour distribution has been modified!
There is another effect known as silver-tipping; this is the sparkling silver tips to the otherwise black fur of Chausies. It is an effect inherited from Jungle Cats (F chaus) and is seen in purebred melanistic Jungle Cats. Affected cats are self coloured, but with a modifier which is new to domestic cat genetics.
The previous sections dealt with solid colours and how they are affected by two types of dilution, three types of colour restriction, agouti ticking and silver/golden shading.
There are genes which control how evenly the hair is coloured i.e. the bands of colour on each hair. In agouti cats, it is easy to see different bands of colour using a magnifying glass . In cats with apparently solid-coloured fur, you would need a microscope. Even though the effect on an individual hair can't be detected, the overall effect on an area of fur is make the colour more or less dense i.e. darker or lighter.
In general the self colours (with plain English descriptions) are:
Colour name
 Plain English Description
Born black, brightens to bright apricot to cinnamon with age.
Pink-brown or hot cream, with a metallic sheen,
Abyssinian/Somali: Non sex-linked cream, Fawn
Chocolate. Genetically black cats with tabby pattern are known as brown tabbies. (Burmese "Brown" is equivalent to black.)
Caramelised blue, cafe-au-lait colour (biscuit colour), cool toned bluish fawn, metallic sheen
Burmese/Tonkinese: equivalent to chocolate
Oriental: Medium -dark brown, equivalent to chocolate
Medium-dark brown
Milk-chocolate (reddish) colour
Buff, dilute of sex-linked red
Foreign : equivalent to black
Abyssinian/Somali : hot cream (non sex-linked cream), equivalent to Light Lilac
Light Amber
Born blue, brightens to pink-beige or fawn with age.
Australian Mist: equivalent to cinnamon
Burmese/Tonkinese : Equivalent to chocolate/chestnut
Pinkish grey (dove grey)
Light Brown
Equivalent to cinnamon
Light chocolate
Burmilla: Milk chocolate
Light Lilac
Equivalent to fawn
Tonkinese: equivalent to sable/seal
Australian Mist: Pink-brown, equivalent to light lilac/fawn. Peach is also seen as a dilute of Russian Blues and may be caramel.
Burmese/Tonkinese: Equivalent to lilac/lavender
Rich ginger red (poor reds are yellowish due to other genes)
Abyssinian/Somali: Equivalent to cinnamon
Abyssinian/Somali: Equivalent to black/brown
Burmese: Dark brown (genetically black)
Siamese: Dark brown (genetically black)
Abyssinian/Somali: Equivalent to cinnamon, honey mink of Tonkinese
Caramel dilution of lilac/lavender
Abyssinian/Somali: Equivalent to black
Abyssinian/Somali: Equivalent to black
Non-albino white, this is the absence of colour.
In all likelihood, there are many other genes which subtly alter the colour e.g. by modifying the hair structure slightly to change the way it absorbs or reflects light or by affecting the distribution of the pigment granules in the hair shaft. The appearance of silver-tipped black cats suggests that hybridisation is going to introduce new colours and effects into domestic cats.
Some colours which have already appeared are still disputed. For example "caramel" is a subtle form of dilution. It does not affect non-dilute colours (black, chocolate, cinnamon), but it changes the appearance of already dilute colours (blue, lilac, fawn). Caramels which are genetically blue cats have a brownish cast while those which are genetically lilac are lighter in tone . So should they have separate colour names e.g. blue-caramel (caramel), lilac-caramel (taupe) and fawn-caramel or should all the slightly varying colours be lumped under the name "caramel". They jury is still out on this one, but it demonstrates the importance of knowing what colours the cat has in its pedigree!
Another new colour, indigo, is described as a richer, darker version of blue. This suggests some sort of intensifying effect acting on diluted colours. However since blues can be variable in hue, there is no confirmation that indigo is due to a specific gene or that it is genetically heritable. The only example I have seen depicted a tortoiseshell cat with blue-black and hot cream patches i.e. to richly coloured to be blue-cream tortoiseshell, but not a red-black tortoiseshell. This could mean a gene with the opposite effect to caramel i.e. it acts on dilute colours only, but it intensifies them. If so, it is probably invisible to the naked eye and only noticed in individuals with the most extreme effects of that gene. The same gene would have no discernible effect on non-dilute colours since there are already at their most intenseNote: since other breeders describe indigo as a darker version of blue, the "blue-black" may have been exaggerated by lighting.
If there is a colour intensifier turning blue into indigo, it could be expected to work on the other dilute colours as well e.g. turning lavender into deep lavender, fawn into rich fawn and cream into rich cream. The differences would probably be too slight to be visible - it is already hard enough to detect the caramels!
According to Inina Sadovnikova, "I believe every breeder has had cats of one and the same colour, but of a different shade . Take a black (brown) tabby, for instance. They range in shades from a light grey with a black pattern to a rich brown with a black pattern. Reds are also very different, from a ginger to an intensive orange. The same concerns blue, I have seen blues so dark that one doubts if they are really blue and not black. From my experience , I tend to think that there is a modifier, though I don't know of any studies of this factor. The litters of my female Konkordia always had at least one kitten coloured intensively, either a very dark black tabby or a very dark red tabby. She has a light shade of colour, but her grandmother is darker and also had several dark kittens in her litters. This looks like a recessive, but one needs a lot more of statistics to prove if and how it is inherited. A dark shade is desirable for red, but at present undesirable for blue. So I don't know if "indigo" has any future."
Strange as it may seem, in some animals the mother's diet can affect coat colour. Recent work at Duke University in Durham, North Carolina, has shown that in a certain strain of mice , the "agouti" coat colour gene can be turned off through methylation. The extent of methylation was dependent on the mother's vitamin intake during pregnancy. (Methylation turns off genes by chemically modifying them). The effect has not been observed in cats, but in theory it could turn genetically agouti (ticked) cats into solid colours.
Some cat shelter workers have noticed apparently self red kittens turning into black adults. Solid black is known to be prone to rustiness through damp or sunlight and evidently, in some cases , to conditions in the womb. Self black kittens are often "rusty" at birth, though few cases are as striking as that of a ginger kitten called "Marmalade" who was entirely black at 6 months old (personal correspondence).
A better documented oddity is that of apparently self red or self black female cats that are genetically tortoiseshell cats. In rare cases, one colour predominates to such an extent that the other is represented by a few isolated hairs.
Copyright 2002 - 2016 , Sarah Hartwell
Bicolour cats go by various names and come in many patterns. They range from almost solid colour cats with a white throat locket or white tail-tip, through to almost solid white cats with black smudges on the nose or between the ears . You may have heard of them as tuxedo cats (white mitts, white belly and white chin with an optional white tail-tip) or patched, pied, particoloured, harlequin or magpie cats (usually white with coloured splashes on the back and top of the head). The term covering all bicolour cats is "piebald" or "white spotted" with some variants of the pattern being called the Seychelles pattern.
The diagram above shows a typical progression from solid colour through to solid white. The number by each diagram is the " Grade " of spotting from Grade 0 (no spotting) through to Grade 10 (white spotting has obscured all of the base colour). The "solid colour" can be one of the true solid colours e.g. black or grey, or a tabby colour or tortoiseshell (the bicolour is then known as a calico and is actually a tricolour). Non-pedigree cats have a diverse range of combinations not recognised in the pedigree world - the "solid" area can be Abyssinian ticked (Aby-and-white), smoke, shaded or tipped. Black-smoke-and white is an attractive combination if not actually encouraged!
The Van pattern seen in pedigree Turkish Van cats and in the Seychellois (a Van-patterned Oriental) is Grade 8 - Grade 9 Piebald and represents the most extreme of the 'Seychelles' patterns. In the Turkish Van, the colour is restricted to auburn (red) or cream patches on the head at the base of each ear; the tail is the same colour as patches, often with darker rings because red and cream are not true solid colours. Although auburn has long been the traditional colour of Turkish Van markings, other colours are being developed within different cat fancies, but in its native Turkey , the Turkish Van actually refers to an all-white cat (Van Kedi).
(Almost) Van Pattern (Grade 8/9 Piebald)
Grade 7 Piebald Littermates
Grade 7 Piebald
The Van pattern is also found in Persian Longhairs in the form of Van Bi-Colours & Harlequins. These often have additional markings on legs, and one or two small splashes of colour on the body. The Seychellois is an Oriental type cat, occurring in both longhair and shorthair forms, exhibiting varying degrees of the Van pattern:-
Seychellois Neuvieme is a white cat with coloured tail and head splashes 
Seychellois Huitieme is white with coloured tail and head splashes plus additional splashes of colour on the legs
Seychellois Septieme has splashes of colour on the legs and body in addition to those on the head and the coloured tail.
British cat fancier Pat Turner defined the different levels of white spotting as: Grade 2 - "White Trim "; Grade 3 - "Mitted"; Grade 4 - " Irish "; Grade 5 - "Saddle"; Grade 6 - "Pied"; Grade 7 - " Chinese "; Grade 8 - "Harlequin"; Grade 9 - "Van". In exhibition -quality bicolour cats, symmetrical markings were preferred .
The placement of the colour patches is variable and related to how the embryo develops and expresses the genes it has inherited. As a result, even more extreme colour restrictions can turn up, for example Wanda below ( photos provided by Peggy Alden-Clapper) is an eyecatching variation on Grade 9 Piebald - all white apart from a black tail, but no splashes of colour on the head or body.
Variation Grade 9 (Extreme Grade 9)
"Moorish-headed" Cat (Variation on Grade 9)
In 1896, Jean Bungartz wrote in his "Illustrated Book of Cats" (in German only): The black-headed or Mohrenkopf (Moorish-headed) cat must be clean white, with contrasting colour on the head and tail. Consistent specimens of this variety are extremely rare and it can probably be regarded as one of the most peculiar colour patterns of the domestic cat. The colour of the head and tail can be either black, grey, blue or yellow with no white hairs except those regularly showing up on the head. As previously mentioned, cats with good and correct markings are highly valued.
Piebald cats are extremely common and varied in appearance. The white spotting can occur with any colour/pattern and varies from minimal white through to almost all white. The smallest amount of white may be no more than a white locket and a small white belly patch, each no more than a few white hairs. Though this pattern doesn't have a descriptive namem the term "locket cat" has been suggested. The image at the top of this page and the description below is a typical progression through the different grades of piebald. Due to developmental effects at the embryo stage, there are further variations on this general theme !
Tuxedo Pattern
White facial markings
At one end of the scale is the white locket, followed by the familiar tuxedo pattern where the belly is largely white. As the degree of white spotting increases , the white spreads up the neck and onto the chin (as shown in the three- quarter Persian above). The cheeks may be white or have white spots and there may be a white blaze (an inverted V) from the muzzle up between the eyes or a white "teardrop" on the nose (as shown in the cat above right). If the neck and chin are white, the front paws are also usually white.
Mask-and-mantle pattern
Saddle pattern
Grade 7 Piebald (with white ringed tail)
As the degree of white spotting increases further, the white extends up the sides of the cat, up the forelegs (stockings) and onto the hind paws. The next step is all white hind legs, white fully around the neck and the white blaze may extend right between the ears. Some cats also have white ear tips. This pattern is sometimes known as "mantled" because the cat appears to be wearing a coloured cape with a hood or mask. The mask-and-mantle is a common bicolour pattern as shown above.
As the amount of white increases further, it simply shrinks the mantle into a saddle. The mask may also shrink back to a "cap" giving the cap-and-saddle pattern (as with the cat in the above centre photo). Further white spotting breaks the saddle up into smaller patches as shown in the black-and-white Grade 7 piebald cat. Sometimes one or more white rings encircle the tail - for some reason this ringed effect seems more common in tabbies.
With any degree of spotting, there may be coloured smudges on the cheeks, chin or nose. Some cats also have black toes on otherwise white paws.
Jean Bungartz described two bicolour patterns in his 1896 book "Die Hauskatze, ihre Rassen und Varietäten" (Housecats, Their Races and Varieties ) in " Illustriertes Katzenbuch" (An Illustrated Book of Cats). His description of the "masked cat" is the tuxedo pattern, which he describes as "sometimes the tail-tip is white also. The eyes of this variety are bright yellow with black rims. Regular and sharply defined white patches create the most beautiful Mask Cats which have many admirers."
Bungartz describes a less familiar bicolour he calls the black-headed or Moor -headed cat (Mohrenkopf) which was clean white, except for the head and tail, which were black, grey, blue or yellow with no white interspersed "except those showing up regularly on the head". Consistent specimens of this variety were extremely rare and valuable . His illustration depicts a cat with wholly black head, but it is possible he was describing the Van pattern.
It is possible to combine piebald with bicolour. Bicolour Siamese have been bred in Europe to a mixed reception. A few Himalayan breeders breed bicolour Himalayans, using bicolour Persians to introduce the white spotting pattern. Paul Beall, Richmond, Texas is one such breeder. Paula 's photo (below) shows a bicolour (piebald) Himalayan, but unfortunately this cat has not produced piebald-point kittens and Paula has decided not to reintroduce the gene from Persians.
When the amount of white is small (under 40%), it is called low-grade spotting and comprises the white belly patch, mitts, locket and blaze. In medium grade spotting, the amount of white varies from 40% to 60% of the coat and is the typical pattern of a show quality bicolour (a mask and mantle effect). When it is extensive (more than 60%), it is called high-grade spotting - the Seychellois or Van pattern.
Piebald spotting is a semi-dominant gene with very variable expression. Low grade spotted cats and some medium grade, spotted cats are heterozygotes i.e. they have only one copy of the white spotting gene. Other medium grade spotted cats and all high grade spotted cats are homozygotes i.e. they have 2 copies of the gene. Where cats are in the medium spotted range it is generally impossible to know whether they are heterozygotes or homozygotes unless they are bred to a cat known to be either homozygous or heterozygous. To further complicate matters for breeders, some apparently non-piebald cats are really piebald cats whose white bits are so minimal they might be no more than a few hairs in the groin or at the tip of the tail!
In January 2016 , it was announced that piebald patches form when cells fail to develop in the womb. The gene for white spotting affects the embryo cells (melanoblasts) which will become pigment-producing skin cells (melanocytes) which make the pigment for hair. Pigment cells move and multiply as an embryo grows and there aren't enough cells to cover all the skin, so the animal gets a white belly. The findings were published in the journal Nature Communications. The pigment cells 'fail to follow instructions' during early development . They move and multiply randomly as an embryo grows, without complex cell-to-cell communication sending them in one direction as once thought. The University of Edinburgh 's Dr Richard Mort said that the cells move and multiply at random which is not what was expected. The University of Bath's Dr Christian Yates said: that piebald patterns could be caused by a faulty version of a gene called kit. What the researchers found was counter -intuitive. Previously it was widely thought that the defective kit gene slowed cells down, but instead they found that it reduced the rate at which the pigment cells multiply. This did not surprise cat fanciers who had noticed that pigmented patches could fit together like a jigsaw and likened the process to “plate tectonics” where pigmented patches drift across the embryo’s skin leaving unpigmented areas inbetween the patches. Researchers at the Universities of Bath and Edinburgh said that in addition to kit, there are many other genes that can create piebald patterns, but their the mathematical model can explain piebald patterns regardless of the genes involved.
This wasn't entirely surprising to many cat fanciers with an interest in genetics or embryology! Independently of scientific researchers, and based on observation, fanciers had some ideas of their own, which have turned out to be close to the mark.
Many cats have patches which look as though they could be fitted together like jigsaw pieces; for example a coloured spot on a leg might correspond to an inlet on a coloured patch on the flank, exactly as though a piece of coloured area has broken off and migrated elsewhere. Spots could end up almost anywhere depending on the timing of cracking, the size of the coloured domains, and the trajectories they take over the embryonic surface as it grows. Terada and Watanabe found it possible to fit all the coloured areas of cat coat together. The seams can then be projected onto the surface of a sphere (the embryo). As the sphere expands, the coloured area cracks apart. Think of a balloon covered in solidified chocolate: the balloon can expand, but the chocolate can't. The cracked solid surfaces then gave patterns just like those found on bicolour cats. The swirled patterns in particular fit this hypothesis.
Part of this theory was that the patterning of black and white was the result of the skin surface "cracking" during early embryo development. The skin of such bicolour cats at an early embryo stage would be basically pigmented, but the dominant S (white spotting) gene, causes the pigmented surface to crack into domains or islands . These islands drift apart over the embryonic surface as the embryo grows, but the pigment cells don't multiply fast enough to fill the spaces between the island . That leaves white areas in the regions between the islands of pigment. It may help to think of it as similar to the movement of the earth's continents with areas of sea inbetween. It is just as though the white areas were scar tissue produced by the cracking. There are not enough melanocytes available to fill the white areas as their surface expands. This means that the black domains can end up pushed together to form a single tuxedo style black area (albeit there may be some small white markings in this single black area). The white belly area might be a ventral (belly) seam from a ventral crack earlier on - it is suspected that the belly area expands greatly during embryo growth . Megacolon in cats and exposed gut conditions in some rabbits upholds this theory. Black feet could indicate a black domain that has been pushed to the foot extremity by the expansion of the ventral region at the same time that the limbs are being formed .
Where the white spotting occurs over the eyes, it may affect the eye colour. Thus a few bicolour cats have blue eyes. Another interesting effect of white spotting is in tortoiseshell cats. Tortie cats with little or no white tend to have brindled coats with intermingled black and orange hairs. However, the more white there is, the more the black and white will also be separated out into patches instead of being intermingled. This is also explained by the mechanism detailed in the 2016 report findings. The black pigmented cells that have moved across the embryo surface multiply to form black islands (clonal patches), while the red pigmented cells that moved across the surface multiply to form red patches.
Above: "Olga", an attractive brown bicolour owned by Sarah Richie
It used to be thought that when the melanoblasts arose from the "neural crest" - the area along the back of the embryo -they migrate all over the body during formation of the skin. Where cells failed to reach their allotted positions before the skin was fully formed, those areas lacked pigment. This seemed to explain why the white is most often found on the paws, belly and chest - those areas are the most remote from the neural crest and take longest to reach. The slower the migration of cells, the less colour there will be. It also explained why the back and the tail may be coloured in an otherwise all white cat - those areas are closest to the neural crest and the pigment cells didn't have to migrate very far.
Another theory involved either of two cellular mechanisms in white spotting that "turned off" pigment. One mechanism was apoptosis (programmed cell death ) reducing the melanoblast (pigment granule) population. In other words, the colour cells migrate over the whole surface of the embryo, but then selectively die out. The other cellular mechanism involved intracellular chemical communication whereby colour cells are biochemically turned off in certain areas. Both of these suggest a chemical gradient so that cells at the extremities tend to be first affected and stop producing colour.
Another hypothesis for the distribution of white was originally presented in papers published by T Terada and T Watanabe in a 1930s Japanese journal. This hypothesis is now being investigated using computer simulation. There are several "unknowns" with the current hypotheses: the relative frequencies of the 10 grades of white spotting given that white spotted cats may be either SS or Ss; the relationship, if any, between birth order and patterning; and whether the "swirled" pattern is related to any birth defects or any difficulties during pregnancy. The melanocyte migration hypothesis may not contain the whole story, especially where swirled patterns, black feet on white socks and skunk stripes are concerned.
Some cat breeders believed there were flaws in the conventional melanocyte migration theory. For example a breeder working with American Shorthairs has been crossing Van pattern American Shorthairs to bicolour and spotted Van pattern cats since the mid 1990s. She found that the melanocyte migration theory could not account for some of the spotted patterns these breedings produced. Alternative theories from other white spotting genes and mechanisms in other species ( dogs , horse , pigs and goats) also could not account for what was appearing in her cats, particularly with 60%, 70%, 80% and 90% white on a cat. The terminology used differs from the Grades 1 - 9 of the cat fancy; 90% white with a lot of random spots is referred to as Level 15. Selective breeding has isolated most of the white on the cats to a single layer of white. She can now produce solid coloured cats from the mating of two bi-colours/pied/vanish cats. In addition, all of her best breeding cats have black feet. Breeding experiments involved mating a level 15 stud to a solid black, two Level 7 piebalds, and a Level 9 cat. A cat with a large degree of white is most probably homozygous for the white spotting gene and mating it to other white-marked cats which also carry at least one white spotting gene should not, in theory, produce solid-coloured cats. An alternative hypothesis is that the cats have the dominant white gene (the one related to deafness) and that a second gene is causing this to break down so that spotting appears. It is possible to produce coloured cats from mating two all-white cats since each parent needs only one copy of the dominant white gene to make them all white and can carry masked genes for other colours.
There are quite possibly several genes which influence white spotting. For example, the patterns above might not be due to a single gene - there may be several other genes which modify its effects. There are also other piebald patterns which appear to be due to different genes or to cats being homozygous for a modifier gene since the effect is relatively uniform and predictable.
The gloves (mitts) on Birman and Snowshoe cats appear to be due to an incompletely dominant gene. The gloves may vary in length but they are restricted to feet and/or legs. The white markings on the forehead and chest of breeds such as the Snowshoe may also be due to a gene which limits the amount of white. Lockets - those small spots on the throat, chest, stomach and groin of otherwise solid coloured cats also seem to be due to a different gene - one which is normally hidden by the more extensive white spotting of piebald cats. There is also the phenomenon of white toes occurring on otherwise coloured cats.
In the York Chocolate breed, there is a particular white displacement in bicoloured individuals. The placement of white maintains the same configuration in all successive generations. This has been termed "Spotting Particolour" and may be due to an allele (variant) of the White Spotting gene. According to this theory, the White Spotting gene appears to have 4 variants: non-spotted, spotted, particolor, and Birman mitted. Spotted is the dominant form and is variable expressed. Non-spotted is the recessive wild-type and produces a coat without white. The hypothetical Birman allele (or Birman mitted) is also variable, but confines the white spotting to the legs and feet. The hypothetical Particolour allele produces an inverted white "V" with the apex in the centre of the forehead and passing through the centres of the eyes plus a white chin, chest, belly, legs and feet are white. Particolour is also variable and its least expression may be a white locket or white spot on the forehead. The existence of breeds such as the York Chocolate (consistent particolour pattern) and Birman and Snowshoe (consistent mitted pattern) appear to support the existence of a white particolour gene and a white mitted gene.
A pattern which has only rarely been reported in cats is the belt , blanket or sheet marking. This is common in pigs and cattle and in Dutch rabbits where a band of white encircles the animal's body like a belt.
Another cause of white spotting is a somatic mutation i.e. some skin cells have a chance mutation which prevents them from producing pigment. This is not hereditary.
Leukoderma ("white skin"), leukotrichia ("white hair") or vitiligo, is a cosmetic condition that produces a "cobweb" or "snowflake" effect and is most easily seen on black cats. White spots appear on the coat; these become more extensive with age until the cat has a white lace pattern on the black fur. Ultimately the cat may go completely white or be left with diminishing isolated patches of colour. This condition has been seen in black leopards ("cobweb panthers"), humans , dogs and other animals. This must not be confused with the normal sprinkling of isolated white hairs which appear in a cat's fur during its lifetime . "Leukotrichia" is a generic term. Acommon term is "piebaldism" because it causes white patches in the skin and fur. It is an "aquired depigmentation" that occurs during the cat's lifetime, is usually progressive and may be triggered by illness or environmental factors. Ultimately, a cat with leukoderma may become almost entirely white. Antibodies are formed against the pigment-producing melanocytes. The melanocytes are destroyed leading to the white areas. A type of leukoderma has been identified in some Persian cats and these are used as laboratory subjects in the study of depigmentation conditions. Periocular leukotrichia, causes the fur around the cat's eyes to become pale - as though the cat is wearing spectacles.
Vitiligo in a big cat - the "cobweb panthers" that turned progressively white.
Charva with feline vitiligo (Jason Reeves).
"Charva" (Jason Reeves) has vitiligo; she was a black cat with patches of slightly longer/softer black hair. In 2009 she turned 4 and developed a patch of white hair. Since then the patches of white have turned into stripes, spots, and patches. Her skin is turning pink as well due to the loss of pigmentation.
In 2011, Kimberly Sexton of New York City sent these photos of her cat Frankie . Kimberly's 14 year old cat Miko (white with grey markings on his head and tail) had recently died and in his last 3 years had formed a close bond with her younger cat, Frankie, a mackerel tabby. The two cats often slept intertwined. Two years before Miko passed away , Frankie developed a white spot of fur under his neck, while his chin and nose became paler. As time passed, Frankie's white areas spread and new ones developed around his neck and behind his shoulder blades. Kimberly joked to friends that Miko's white colour was rubbing off on Frankie as they slept! Frankie's white areas are likely to continue spreading, but the effect appears entirely cosmetic.
On coloured cats, hair regrowth around scars is often white. Lizzie Ellis (The Feline Rescue Association Inc, Maryland, USA) provided these photos of a grey male cat with white patches due to scarring. Where the skin was injured or burned, the fur has grown back white, not grey. The cat had suffered frostbite injuries. Some dark coloured cats show white hairs in their coat as they grow older - some follicles stop producing pigment, just as humans get "grey" hairs. Unlike the cobweb effect (where pigment loss occurs in patches, like snowflakes or strands of gossamer), age-related white hairs are evenly sprinkled across the body giving a salt-and-pepper effect; there may also be greying around the muzzle. It is a normal part of ageing although cats seem far less prone to getting grey hairs than do dogs. It should not be confused with the white patches found in vitiligo.
While the piebald pattern is generally fairly symmetrical until the white exceeds 60% of the body surface, some cats exhibit a variety of swirled patterns. This may simply be due to the way the embryo developed or it may be the interaction between different genes which affect white spotting. The two cats below are unrelated, but both have swirled black and markings and black markings on the face. Both also have black toes. Coloured toes sometimes occur on bicolours - these can be individual toes or multiple toes. It may even look as though a white-footed cat has paddled through coloured paint, in which case the colour usually extends up the back of the leg. Coloured toes may possibly be another gene (modifier) interacting with the white spotting gene.Note: The cat shown top left has a mild form of radial hypoplasia which has caused her deformed forelegs; she also has a slightly deformed skull .
Swirled Patterns
More unusual is the "skunk marking" - a white dorsal stripe. Because pigment producing cells migrate away from the neural crest, the dorsal area itself usually remains coloured in low to medium grade spotting. The appearance of a white dorsal stripe is unusual and appears to be hereditary.
Photos courtesy of Magnificent Munchkins
Pandora (owned by Bill B, Granby, MA, USA) is a brindled cat with what appears to be an unusual mutation. She has the brindled pattern normally seen on tortoiseshell cats, but the patches which should be red are white! The brindling and facial pattern is typical of tortoiseshell cats, but it seems that 15 year old Pandora has a mutation that prevents her producing red pigment. An alternative explanation is that Pandora is chimera formed when a black embryo and a white embryo fused in the womb; however chimeras tend to have a patched appearance rather than being thoroughly brindled, this makes chimerism a less likely explanation. A third possibility is that Pandora has additional X chromosomes (XXX or XXXX instead of the normal XX female), however this genetic anomaly is associated with mental retardation and physical anomalies/deformities (this is not Klinefelter syndrome , Klinefelter syndrome is only found in males e.g. XXY or XXXY). These two conditions can be identified using tissue samples, but this isn't recommended in an older cat as it involves sedation or anaesthesia. It seems likely that the gene that should produce red pigment is faulty or that some other gene is masking the red pigment out. Since Pandora was spayed before Bill obtained her, it isn't possible to breed her to see if it can be inherited. I have seen the opposite mutation - where a tortoiseshell cat produced red pigment, but not black, resulting in a red, cream and white brindled cat - but this is the first time I have seen a black-and-white brindle where the red is absent.
More brindled bicolours are explained in the separate page on Roan, Tweed and "Salt and Pepper" Colours
During the 1980s, there were attempts to breed shorthaired cats with a black tail, black patches on the head and small black (or other solid colour) patches or spots on the body. Named Chinese Harlequin, it was to resemble cats found in ancient Chinese art. Although still listed by some registries, it appears to now be extinct due to the difficulty of breeding bicolours with consistent spotted markings. A similar "strikingly spotted" cat, the Gao Taem, is seen in ancient Thai art and is described as having, black marked forepaws, black and white ears, black shoulders, two black spots on the back and black shoulders. In total there should be nine horse-like black spots on an all white background. If it existed as a breed, the mutation creating these features has been lost. In all probability it was a form of Seychelles pattern. Some bicolours have black toes or paws and and some breeders have attempted to fix this trait to create a black-footed Van-type bicolour.
Also depicted in Thai art (1676) is the Vichiens Mas which is shown as white with dark ears, nose, paws and whiskers. Although depicted as black and white, it seems to be a stylised or idealised depiction of the seal-point Siamese.
"Belted" means a solid coloured animal with a belt of white around its middle , such as is seen in Dutch Rabbits. This pattern has occasionally been seen in Spanish feral cats. "Sheeted" means a wider the band of white i.e. from shoulders to haunches.
The concept of a white cat with coloured spots, akin to a Dalmatian dog or Appaloosa horse, has intrigued numerous people. In some feral colonies, white cats with numerous small black splashes have been found alongside bicolour cats with the conventional Grades 1 - 9 of white spotting. This suggests the presence of modifier genes which affect the distribution of colour and white. Inbreeding causes genes to double up so that recessive genes and traits controlled by multiple genes become visible. It would be possible to have genes which interact with the semi-dominant white spotting gene such that small patches of colour break through the white or which cause a breakdown in white spotting.
Some breeders report a consistently high incidence of numerous small splashes of colour on the body in certain breeding lines which suggests to them that some other gene(s) is being inherited alongside the white spotting gene. This may see a repetition of the Chinese Harlequin programme.
2013-2014, Sarah Hartwell
Many thanks to Silvia Perego and Lesley Morgan for allowing the use of their photographs on this page.
Note on Terminology: At present, terminology isn't standardised. "Bi-metallic" describes a visual effect, while "sunshine" is the (current) proposed genetic name. In Siberian Cats, sunshine-silver produces the bi-metallic pattern.
For some years, strangely patterned Siberian cats have been turning up. Some are covered in A Torbie Dynasty: A Torbie Dynasty. Caroline Sharp in Germany had several generations of apparently tortoiseshell-tabby male cats. This should be impossible as tortie tomcats are genetically abnormal in some way and even when fertile they should not produce further generations of tortie tomcats. They couldn’t all be chimeras, so there had to be some unidentified mechanism at work.
Other Siberian cats had both silver and golden areas of fur and were dubbed “bimetallic.” This X-colour (mystery colour) looked similar to the partway stages of the amber colour change seen in Norwegian Forest Cats. Siberian breeders had referred to their cats as "golden" but this term clashed with the wide band colour found in Persians, Exotics and British Shorthairs. The official term "sunshine" has been proposed to distinguish Siberian golden from "wide band golden".
At birth, Siberian "Sunshine" resembles the early stages of the amber (ee) colour change in Norwegian Forest Cats caused by a non-extension gene. However, the Siberian cats tested negative for the amber gene. There were no genetic tests for Wide-band or for silver inhibitor, let alone for Siberian sunshine, but it can be distinguished visually and by studying pedigrees. Bimetallic colouration has also been seen in the Kurilian Bobtail and in random-bred cats in the Ukraine .
Judge Lesley Morgan come across a number of strangely coloured cats that had been nicknamed “bimetallic” as they displayed a mix of silver tabby and golden tabby in their coats. The effect was beyond
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