AGCS
AGCS

I am sure that all our members are aware of the 5 different varieties within the Asian group. These are: Asian Self (including Bombay), Asian Shaded (Burmilla), Asian Smoke, Asian Tabbies ( in Ticked, Spotted, Mackerel and Classic patterns) and Asian Semi-Longhair (Tiffanie). Apart from the Selfs, the accepted colours of Asians are black, blue, chocolate, lilac, caramel, red, cream, apricot, black tortie, blue tortie, chocolate tortie, lilac tortie, and caramel tortie in full expression colours, plus the Burmese expression of all 13 of these. All of these 26 colours can also either be silver or non-silver (standard). The Selfs, of course, are accepted in full expression colours only, the Burmese expression colours being registered as Asian Variants - that is, except for the Tiffanies, where it is quite acceptable to have a Burmese expression colour "self" cat. I put "self" in inverted commas, because, as no doubt you all know, a Burmese is not a Self cat. (more on that later).

Leaving the Tiffanies aside for the present, as they can be of any colour or pattern, we have 4 varieties: Shaded, Smoke, Self and Tabby. These can be further subdivided into Agouti (Shaded and Tabby) and Non-agouti (Self and Smoke). An agouti is actually a type of South American rodent which has a characteristic coat pattern. Take a look at any tabby moggie and you will see that the pattern consists of 2 distinct components: the (usually) black stripes or blotches, and the area between the markings, which consists of hairs having alternating bands of black and a yellowish colour. It is this background coloration which is known as agouti, and is a constant feature of all Tabbies. Agouti is the natural, wild-type pattern of all cat species, and in fact, all cats, patterned or not, are genetically Tabbies, whatever their outward appearance! Agouti coloration is produced by what is known as a dominant gene, and as it is genetic convention to symbolise dominant genes by uppercase letters, agouti is symbolised by "A".

To digress briefly into basic genetics - all characteristics of a species are controlled by genes. In biochemical terms, a gene is nothing more than a sequence of nucleic acids, which in turn is the "code" for building a particular protein. Each gene is part of a much larger structure composed of DNA, which is known as a chromosome. Cats have 38 chromosomes, humans have 46. These chromosomes are present in every cell in the body. Therefore, there are many thousand of genes in each individual, and only a few are of interest because they control certain characteristics such as colour or coat length. All of the different colours, patterns and coat types that we see in cats have come about as a result of genetic mutation. Mutation occurs when the normally perfect copying process of DNA during cell division fails and an inexact copy of a particular gene is made. The original gene and its mutant form are known as "alleles" and they occupy the same position, or "locus" on a chromosome. When fertilisation occurs, the developing embryo receives genes from both parents, so will inherit characteristics from both; this may include one or more mutant genes. It is important also to remember that genes are inherited in pairs - one from each parent. A cat having 2 copies of a particular gene is known as homozygous, e.g. a Burmese is homozygous for the burmese gene. A heterozygous cat has a pair of dissimilar genes, e.g. a Bombay with a Burmese parent will be heterozygous for Burmese gene (and as the gene for full colour is dominant to the burmese gene, the cat will appear black).

Returning to the agouti gene, as we have noted, it is dominant. This simply means that a cat only needs one copy of the gene to be agouti (i.e a Tabby - or Shaded). As it happens, one of the first mutants to be found in the cat was that of self black. Many wild cat species have a black or melanistic variety (e.g. the black Panther is a melanistic Leopard). The mutation changes the agouti background of the normal Tabby such that the whole cat appears black. The mutant non-agouti gene has been found to be recessive, and is therefore symbolised as "a". For a cat to be non-agouti, it must have 2 copies of the recessive a gene, whereas a Tabby can have genetic constitution AA or Aa. Hence it follows that a mating between 2 non-agouti cats can only produce non-agouti (Self or Smoke) offspring, whereas mating agouti to non-agouti will produce Self, Tabby, Shaded or Smoke.

Having just mentioned Shaded and Smoke, some explanation of these terms is probably a good idea. The first Burmillas were produced by mating a Chinchilla with a lilac Burmese. The resulting kittens, 4 Black Shaded Silver shorthairs, were living proof of the action of dominant genes! Black has just been explained above - Silver is produced by a gene known as Inhibitor (I) which inhibits pigmentation of the yellow coloured bands in the agouti area of a Tabby's coat, giving the striking appearance of black markings on a nearly white background - the Silver Tabby. As for the Shaded - opinion is divided on whether or not this is due to a single gene (which Roy Robinson and Pat Turner have called Wide-Band, Wb), or is the result of a group of genes. Personally I believe the latter to be the case. The effect does however appear to be dominant. As the name suggests, the result is widening of the banding on agouti hairs, pushing all the black (or whatever the basic colour of the cat) pigment towards the tip of the hair shaft. This effect has been taken to its limit in the Chinchilla and British Silver Tipped - the cat appears nearly white with minimal black tipping and virtually no distinguishable tabby markings. It's easy to see that they are not white cats by examining the paw pads and eye rims, as these are not pink as in a true white cat, but black. It is, of course, perfectly possible to have a Shaded cat that is not Silver. We do not distinguish between Golden and Standard in the Asians - they are simply registered as non-Silver. Golden is said to be homozygous for wide-banding and Standard is heterozygous - but that is best left for the moment! So, a Burmilla is simply a Tabby (of any pattern) showing the effects of the wide-band gene(s), with or without Inhibitor. GCCF Burmilla breeders prefer their cats to be more deeply coloured than a Chinchilla or British Tipped, although some people would argue that a true homozygous Silver Shaded cat should be virtually white with no tabby markings. As for the Smoke - nothing more complicated than a Self cat with Inhibitor. The ideal Smoke should at first glance appear to be a Self, with the white undercoat visible when the coat is parted. However, due to variable expression of Inhibitor, and the fact that some Smokes may also have wide-banding, the perfect Smoke is difficult to produce, especially in a shorthaired cat.

Having said that some Smokes may have wide-banding, the same also goes for Selfs. This is more likely if the Self derives from a Chinchilla background, but cannot be ruled out in any case. The effect will be to produce an unsound coat, which is not an uncommon problem in many of our Selfs. The influence of the Burmese gene has to be considered as well. I mentioned at the start of this article that a Burmese is not a self cat. This is especially noticeable in the chocolates, which often have a considerably darker "mask". In addition, the coat of a Burmese is naturally unsound in that it becomes paler towards the roots. The burmese gene is in fact one of a series which goes from full colour to albino via Siamese. The widespread use of Burmese in the Asian breeding programme has undoubtedly had an effect on soundness of coat in some of the Selfs. To eliminate unsoundness, it would probably be necessary to reduce the use of Burmese - at the risk of unacceptable degrees of inbreeding. Finally, I should like to mention the different Tabby patterns. We've looked at what makes a cat a Tabby (the agouti gene), but what pattern is it going to be? The native or wild-type pattern is the mackerel with its thin vertical stripes on the body and rings on legs and tail. The classic or blotched Tabby is also fairly common in non-pedigrees. The Abyssinian or Ticked pattern is unusual in that it is characterised by a general absence of markings on the body, but does have leg and tail rings. However, in pedigree Abyssinians, even these markings are absent (could the Aby really be a Shaded?!) The fourth pattern, the Spotted, is probably a variation of the Mackerel or Classic in which the stripes / blotches have broken up into spots or short bars. At the beginning I said that all cats are genetically Tabbies- this is because they will all carry genes for one (or two) of these patterns. Try looking at your Self kittens - you will probably see a pattern if you can catch it in reflected light - if you don't see a pattern, the chances are it is carrying Ticked! The tabby genes also have an order of dominance - Ticked being the most dominant, followed by Spotted, Mackerel and finally Classic. In fact the latest theory proposes that the Spotted pattern is due to a modifier gene which acts on either Mackerel or Classic, and that there are actually 3 different alleles involved in determining pattern (ticked / nonticked, mackerel /classic and spotting modifier / non spotting modifier. This does explain how it is possible to produce all 4 tabby patterns in a single litter. The Ticked Tabby predominates in the Asian group, again due to the Burmese influence. The vast majority of Burmese have an underlying Ticked pattern - this is why they are, on the whole, clear-coated, and it is also why many of the Asian Ticked Tabbies have "lost" their leg and tail markings. It is difficult to see how we could establish the other Tabby patterns in the Asian group without outcrossing to other breeds. Unfortunately, many of the cats registered as Tabbies are in fact Shaded - their pattern is very superficial when examined closely. I believe that it is very important for breeders (and Judges) to be aware of this and to be able to distinguish a Tabby from a Shaded. However, that subject could quite easily fill another article.

© Naomi Johnson 1996 / updated Jan. 2000