"COPPER" PHENOTYPE IN BRITISH TIPPED SHORTHAIRS (ULTRA-WIDE-BAND)
This article looks at the appearance of "ultra wide-band" in Tipped and Shaded Golden British Shorthairs. These are also known as Golden Chinchilla and Golden Shell. The term "copper" was adopted by Linda Petersson Wahlqvist to describe Golden Shell cats with white toes, white undersides, golden colour with the dark tips (e.g. black or blue) restricted to the tail tip and an absence of dark nose-liner. These phenotype deviates from the standard for tipped cats, but is becoming prevalent in Russia and in some German lines of British Golden Shorthairs. "Copper" is not an official term, but it allows breeders to describe the phenotype in a single word.
Emergence of Extreme Golden in Russia
This section is an English language summary of information on the Russian website Shaded Cats
Traditionally, gold and silver were seen as related colours belonging to the category of tipped colours. Ideally the tipping should not exceed 1/8 of the hair, and there should be no trace of tabby markings. This was achieved in silvers, but not in goldens. Typically, golden cats had ticked fur with 2 or more bands of colour, and they had residual markings including rings on the tail. Traditional golden cats still had the genetic colour – black, blue etc – visible.
The new goldens that appeared in Europe were not ny11 (tabby-based goldens) they were ny25 (ticked-based goldens). The new goldens attracted a lot of interest in Russia. C In adulthood the cats had extremely uniform tipping with no hint of a tabby pattern. There were no markings on the chest and no wide rings on the tail. These cats had a huge advantage because they were closer to the “ideal” golden colour in the standard. But they also were deficient against the standard because the hairs were not tipped with the genetic colour (and the nose leather did not have a dark outline which should be present in agouti cats). The new extreme golden and new silver cats increased in popularity with many breeders being drawn into it, not always because they like it better, but because it was competitive and was “the way to go” to succeed at shows.
Some breeders tried to remove the pattern and to make the colour as warm and bright as possible. To accomplish this they outcrossed to genetically ticked tabbies to remove any trace of a tabby pattern. Ticked-based silvers and goldens still had ticked hairs (pale grey in the case of silvers, yellow in the case of goldens), but this was not detrimental to the overall effect. Breeders, particularly in Russia, continued to select the brightest gold chinchillas to breed with and the brightest, most orange, golden cats had pale toes and pale markings around the eyes. Some cats were a pale yellowish gold with nearly-white toes. Some breeders worried that this bleaching turned golden cats into something else. Others believe that there is no really bright golden colour without some degree of bleaching. This caused debates over which was the true golden colour –gold with not bleaching, or bright gold with bleached toes and bleached underparts. The bleached (or “excessive”) version was termed “Akita” after the Akita Inu (Shiba Inu) dog, and is also known as “copper.” Nobody stopped the breeding of the extreme golden cats with bleaching and the colour was seen as more distinctive than the ordinary golden-red colour, which was too much like an ordinary red-ticked cat. Many of the Russian breeders do not feel the need to separate the Akita/Copper cats into a new colour, but see it as a natural evolution of colour to create the perfect golden cat. Even the pale goldens are not a problem – while they may not be show-quality, they can produce bright red kittens.
Investigations in Europe
Shaded and tipped (shell/chinchilla) are due to the dominant Inhibitor gene (silver) + presence of Wide Band + the Ticked Tabby pattern. In silver cats the dominant Inhibitor is present. In golden cats, the dominant Inhibitor is absent. Wide Band is independent from the Inhibitor gene and though "Wb" is treated as a single dominant gene for simplicity, it appears to act as polygenes with an additive effect. In ticked tabby cats without silver, Wide Band restricts the pigment to the end of the hair leaving a pale golden band between the skin and the pigment. Through selective breeding, this effect has been maximised. The variability of the wide band suggests we should talk about Wb, Wb+ and Wb++ to describe cats with normal, intermediate and greater degrees of Wide Banding.
The appearance of this phenotype was investigated by tracing the family trees of cats that displayed it. This showed that there was no single mutation or common ancestor, but rather it was the interaction of mackerel tabby (ny25) with chinchilla (ny11) and most likely an accumulation of Wide band polygenes. Alongside the "copper" phenotype were some chinchillas where the black pigment at the hair tips was reduced to almost nothing. Only the eye colour and paw-pad colour showed that these were truly Chinchilla cats and not solid white cats. This shows that the Ultra Wide Band effect operates on cats with silver as well as without silver. Cats without silver and without Wide Band are cool-toned ticked tabbies. Because ticked tabby is on a different locus from classic/mackerel/spotted tabby, these markings can sometimes breakthrough the ticked pattern to some degree.
Another possibility is a recessive allele (gene variant) at the E (extension) locus, such as "amber" (seen in Norwegian Forest Cats). These usually reduce the amount of black and the effect can range from no black whatsoever (seen in chestnut horses) or still allow some black (as in amber cats) while not affecting the skin pigment. Amber cats are basically black cats with a colour modifier that affects the deposition of pigment on the hair shaft; in non-agouti ambers the nose remains black and in agouti cats it remains pink. The "copper" cats with black pawpads and tail-tips, but without black on the body are suggestive of a recessive E allele.
For example, based on research into Siberian "Goldens" (Golden-Sib) there might be a series of alleles at one locus: non-golden >> golden >> copper (in Siberians there appears to be a series Non-Golden-Sib/non-Sunshine >> Golden-Sib >> Sunshine).
A further possibility would be a new dominant mutation at the A (agouti) locus. In dogs, this creates the fawn/sable colour, often with black shading or tipping long the spine. Similar dominant A alleles occur in several other mammal species. In domestic cats agouti (ticked hairs) and non-agouti (self/solid colour) are well known. It is possible that unidentified mutations of the A gene have occurred in the domestic cat and are showing up through selective breeding for colour. At least two other variations at the A locus occur in wild cat species. A mutation at the E locus or A locus would still interact with any Wide Band polygenes to further restrict the colour on the hair shaft.
Although the true "copper" phenotype involves tipping/ticking, what do tabby-marked related cats look like? i.e. how does the ultra wide banding affect non-ticked cats? It seems to turn the markings to gold and the only evidence of the black marking colour is seen at the tail tip and on the paw pads.
The following colour-coded family trees should be opened in new windows so they can be read at full size! They show the relationship between ny11 and ny25. They don't answer the question of what gene(s) cause the copper phenotype. They are aimed at showing common ancestors of copper cats and different combinations that have led to the copper phenotype.
Then came the question of how many lines traced to a Persian Shaded Golden called Esteban von Aemstelhove (or van Aemstelhove). Mated to Marvellous Golden Desiree, he produced Goldstern de Broekloni who was a prolific stud used in Silver and Golden British Shorthairs. Esteban von Aemstelhove was noted for his very warm golden coat and it seems likely he had a very good Wide Band trait that was passed down in his descendants. His great-great grandson was Marvellous Gold Radetzky, another prolific stud who appears behind several "copper" British Shorthairs. According to the databases, Esteban von Aemstelhove's other offspring remained in the Persian/Exotic gene pool.
This can be traced even further back to another common ancestor called Polar Jenko. There is an Abyssinian a long way behind Angelika Niesel’s Polar Jenko, born 1988. Ancestors included Oriental cats a Russian Blue and registered pedigree unknown cats (possibly with Aby blood?). There is almost no information on his “van Wier en Gouwe” ancestors except that Amor van Wier en Gouwe’s parents are Chinchillas. There are many other cats that are untraceable. Also in that pedigree we find Danilo of Great Yarmouth (PER, cannot be traced) bred to Aminda de Malpertius (Russian Blue) and the offspring registered as British Shorthair. Polar Jenko descends from the Dutch Potentillas line. Also back then the silver SH cat was being developed. Polar Jenko was very valuable for breeding silver British cats, as he represented of a completely different line, and was very compact and massive. He also had a valuable set of genes: he carried the Colourpoint gene and apparently brought the sorrel (cinnamon) gene to golden cats. Jenko was in the possession of Mrs. Ursula Muller of vom Wahrberg cattery, since Abdullah, another Oaxaca – Anais stud, did not get along with Polar Jenko. If Polar Jenko carried sorrel/cinnamon it came from an ancestor 8 generation ago on his sire's side. Russian breeders saw it as a welcome and unexpected gift from imported Oaxaca and Wahrberg cats.
UPDATE: According to a breeder, the cat Viola vom Wahrberg, who links many pedigrees to Polar Jenko, was not actually Jenko's daughter. Jenko did not carry dilution. The breeder had another young male at the time named Marvellous Rembrandt. Golden Sahra vom Wahrburg had 6 kittens, 3 were blue-golden and 3 were black-golden (grey colour). It could be seen that the 3 blue-goldens were from Marvellous Rembrandt, a confirmed dilute carrier. Jenko never gave dilution, but point cats. Jenko never gave reddish (copper) coloured kittens. Over several generations the colour got warmer. The first "copper" colour cat in many opinions was Marvellous Radetzky.
So now to trace Marvellous Golden Desiree and Marvellous Golden Radetzky (highlighted in previous trees) back to Persians, American Shorthairs and Scottish Fold Shorthairs. Rather naughtily, the American Shorthairs are shown on some databases as BRI (British) which hides the ancestry of some of the cats. I've highlighted the outcrosses and noted the breeds, and also highlighted a couple of influential cats. Behind some of the "copper" lines are ny12 Persians (I haven't traced further back). It's obvious that these outcrosses will result in British Longhairs further down the line.
Below shows Persian and Exotic Shorthair influences. This moves the British Shorthair even further away from its original type and closer to the Persian/Exotic type as well as affecting the silver and gold colours.
Now to look at some of the other cats that have sneaked into the British Shorthair gene pool (as a request from breeders wanting to avoid those influences). Nirvani Du Mouli D'Amelghem is descended from Scottish Fold straight-eared variants. Sunnyland lines and Goldenen Winkel lines trace back to Selkirk Rex variants. British Shorthair is an allowable outcross for Selkirk Rex, but the straight-haired variants don't usually go into British Shorthair lines. You can also see that Andy vom Wahrberg was a prolific stud who has also contributed to Selkirk Rex lines.
Marina Bessergeneva has a "copper" phenotype cat, Noble Cats G*Nolan. His family tree is also shown. The photos show how pale some areas are and the extremeness of the restriction of colour to the very end of the hair. The fur is definitely tipped and not visibly ticked, but it’s possible all ticking has been pushed to very end of the hair. A search online finds that some breeders of the "copper" phenotype are also breeding ticked tabby British Shorthairs. Now that ticked tabby is reintroduced into the British Shorthair, allowable crosses could add this gene to tipped cats. It is known that one breeder crossed British Shorthair and Abyssinian to get a warm n25. A judge in Turkey suggested that some breeders may have used the Abyssinian previously in order to reduce ghost markings and get a warmer colour. Discussions on this have been found in Russian forums, but there is no direct evidence.
SUMMARY OF IDEAS FOR INVESTIGATIONIS WIDEBAND THE CORIN GENE?
Xiao Xu, Ph.D., Associate Investigator (Laboratory of Genomic Diversity and Evolution, School of Life Sciences, Peking University, Beijing, China), identified the CORIN gene variant CORIN p.H587Y to be responsible the wideband gene white and golden tigers, but not responsible in chinchilla cats. Several years ago, his team identified the Tabby gene and this was published in the Science journal. Stripeless (ghost-striped) white tigers and golden tigers visually resemble extreme chinchilla and golden cats which made CORIN a candidate gene for chinchilla and golden in cats. In deer mice, the Inihibtor gene (A locus) was found to cause the wideband effect. So far only two wideband genes have been identified in mammals – CORIN in tigers and Inhibitor in deer mice. Because golden is related to the number and width of bands on the hair shafts, another candidate is AGRP (agouti related protein). (Xu X, Dong GX, Schmidt-Küntzel A, et al. The genetics of tiger pelage color variations. Cell Res. 2017;27(7):954-957.)
Leslie Lyons of the Lyons Feline Genetics Laboratory has been researching silver and golden for a number of years without identifying a gene, and wants DNA from the extreme goldens (so-called coppers). The emergence of the copper and extreme chinchilla phenotypes may prove fresh impetus for research and new genetic variations for study.
IS WIDEBAND ON THE TICKED LOCUS?
Is it possible that wideband in cats is at the ticked locus? The extreme silver and the copper phenotype are both associated with ns25 and ny25 i.e. ticked tabbies. Does a gene at this locus cause a change in frequency and/or width of ticking?
DOMINANT WITH ADDITIVE EFFECT?
To date, textbook assume the golden colour in domestic cats to be a recessive trait. Could it be a dominant gene with additive effect i.e. one copy of the Wideband gene (Wb/-) gives golden, but 2 copies (Wb/Wb) gives a more extreme golden effect? The various expressions of golden could be due to different combinations of inhibitor, ticked and wideband. This is already an accepted theory by many cat breeders, based on pedigrees and visual observation, but there is not yet any scientific evidence for this.
Black ticked (n25) - i/i, Ti/-, -/-
Golden ticked (ny25) - i/i, Ti/-, Wb/-
Golden chinchilla (ny11/12) - i/i, Ti/-, Wb/Wb
Black silver (ns25) - I/-, Ti/-, -/-
Shaded silver (ns12) - I/-, Ti/-, Wb/-
Chinchilla silver (ns11) - I/-, Ti/-, Wb/Wb
Usually, a dominant effect is caused by a gene gain-of-function (increased activity of the gene), and a recessive effect is caused by a gene loss-of-function (decreased activity of the gene). If the Wideband gene is dominant then increased activity of the CORIN gene would reduce the pheomelanin (red) bands, not make them wider. However, if the I gene (A locus) has increased activity it could cause the wideband effect in cats the same way it causes wideband in deer mice.
IS COPPER DUE TO AN INDEPENDENT MODIFER?
The Copper colour (the provisional symbol “cp” is used) might be an independent recessive modifier gene affecting Wideband and “copper” phenotype cats might be i/i, Ti/-, Wb/-, cp/cp or i/i, Ti/-, Wb/Wb, cp/cp genotype (homozygous no silver, dominant wideband, ticked tabby, homozygous copper modifier). If this theory is correct, a cat with I/-, Ti/-, Wb/Wb, cp/cp genotype should be nearly white – and this is indeed the case with extreme chinchillas that are closely related to “copper” cats. Extreme silvers look almost white apart from their eye colour. However, not all tipped (chinchilla) cats are ticked tabby cats so the presence of “Ti” is not necessary to get the copper phenotype.
THE CINNAMON AND CHOCOLATE CONNECTIONS
Johanna Nordin (Sweden) has also been investigating the copper phenotype from another direction. Her first thought when she saw the red-white golden cats was the Abyssinian sorrel colour, which is cinnamon + ticked, and she started thinking that the cinnamon allele of the bl gene might have a role in the copper cats. She discussed this with an experienced breeder of golden and silver British Shorthairs who has been breeding them for some decades. The breeder told her that the "coppers" are carriers of chocolate and that there might be some crossbreeding with Abyssinians in the copper-lines but that was not the official standpoint.
Johanna then went on to check out the expression of the chocolate colour in Abyssinians (23b). Chocolate ticked Abyssinians resemble the red-white golden coats of "copper" phenotype British cats (such as Sundust Macavity whose image can be found online), but with the addition of having more white on the chin and toes. They also had the same black at the end of the tail tip. In Abyssinians the colour is described as “rich copper brown ticked with dark chocolate; Base Hair - Rich Apricot.” So perhaps the copper cats are ticked chocolates with Wide band (and maybe other polygenes) and without inhibitor (golden ii = non silver). This could explain why the coppers have more white on the chins, toes and undersides than the Abyssinians (which don’t have the wide band and other polygenes) and a lighter base colour. Side by side, there is a similarity, allowing for the brighter and more whited appearance of the copper shorthairs.
If Polar Jenko carried sorrel/cinnamon, as suggested by Russian breeders of the "new golden" phenotype, it came from an Abyssinian ancestor 8 generation ago on his sire's side. Russian breeders saw it as a welcome and unexpected gift from imported Oaxaca and Wahrberg cats.
If the coppers were tested and found to be chocolate and cinnamon, that would make them (in EMS terms) "chocolate golden tipped/ticked = by 11 (25)" or "cinnamon golden tipped/ticked = oy 11 (25)."