In genetics we have a code. This code is compilation of groupings of letters that represent specific genes that express as various character traits. Some are dominant (denoted with a capital letter i.e. A, B, C ) and typically over powers the recessive trait (denoted with a lower case letter i.e. a, b, cs) and some need to be paired together to produce specific new traits. Each trait set will include 1-3 letters on each side of a forward slash. The first 1-3 letters is a trait from one parent. The second set of letters is the trait from the second parent. In the Bengal breed we have several “letters” that work together to design a cat’s physical features (phenotype) as well as traits you can’t see but they still carry (genotype). The genes that are carried when combined with another parents gene can produce a cat that looks nothing like the parents for example two brown cats producing a cream colored cat. These two cats each didn't express said trait but carried the genes required to produce this cream colored offspring. Note: Technically speaking many of these alleles cause pattern effects, color modifications etc they aren't colors per say but for the scope and understanding of cat color genetics we will refer to them as colors.
Note: Naming terminology is based on The International Cat Association (TICA) and how cats are registered with the organization.
Relevant Bengal Cat Alleles
“A” Alleles (an allele is a variant of a trait that is contributed to the offspring, one from each parent). This specific allele defines patterned or non-patterned cats that operates by turning on and off genes that are responsible for light and dark pigment distribution. It is referred to as agouti or non-agouti. When you look at the individual hair shaft, the agouti produces a hair shaft that has bands of color where as the non-agouti hair shaft is one solid color. While in general agouti isn't really a color as it primarily affects pattern and pigment distribution, the "A" alleles will appear on genetic color tests.
A- This gene is the domestic (from domestic non-Asian leopard cats) Agouti. This results in a patterned cat. It is a dominant trait. The hair shaft of an agouti cat has bands of color.
a- This is the domestic (from domestic non-Asian leopard cats) non-agouti gene, part of the puzzle for charcoals and solid colored cats. This is a recessive trait. The hair shaft of a non-agouti cat has a single band of color.
APb- This is the Asian Leopard cat (ALC) agouti gene, part of the puzzle for charcoals. It is incomplete dominant meaning the trait is not dominant or recessive. The dominant trait is diluted in relation to the recessive gene, producing a NEW phenotype.
Combinations produce differently patterned cats A/A is a cat with pattern that can have spots, rosettes, or marbling A/a is a cat with pattern but when paired correctly can produce a non-patterned solid cat due to the recessive non agouti gene Apb/A is a cat with pattern that can have spots, rosettes or marbling a/a is a solid cat (one solid color) some of these cats have a ghosting effect where some pattern can be seen. The tabby pattern is still there, its just better masked.
APb/a for many is a charcoal (at this present time, but there is evidence suggesting charcoal is more than a genotype )
You cannot carry for charcoal. You either are or you are not a charcoal
Charcoal is a pattern effect that can change pattern and color
The Charcoal is recognized by TICA and CFA.
Click here for more on APb
APb/APb is a patterned cat and for many not considered a charcoal (many theories point to the fact that charcoal is more than a genotype and that APb/APb cats can be charcoal) Alone this trait represents patterns, but combining the A allele with color point, inhibitor and dilute genes can alter what the outward expression of the cat looks like in regards to color. More on this below.
It is suggested that “A” is dominant over “a” and either dominant or is incomplete (a trait that isn’t fully expressed and may be a combination of both traits) with APb and both are dominant over “a”. There are other A alleles like A2 H2, H3, H4 and H5. These agouti genes are dominant and express as patterned cats. Christopher Kaelin PhD professor at Stanford University has determined they come from various subspecies of asian leopard cats that have been traced back to original ALC's used to create the breed. These are seen in most Early Generation (First generation-third generation) bengal cats and are not very common in most Stud Book Traditional (all cats that are 4th generation or higher) cats.
“B” allele is the primary color. For almost all Bengals this is black. Even if a cat is brown they are typically referred to as a black spotted…. The only time this changes is with chocolate or cinnamon Bengals. These are recessive genes to black.
B- This represents Black. This trait is dominant
b-This represents Chocolate. This trait is recessive BUT dominant over cinnamon
b1-This represents Cinnamon. This trait is recessive to all other "B alleles B/B is Black as the primary base color b/b is Chocolate as the primary color
b1/b1 is Cinnamon as the primary color
When these alleles are combined with other alleles such as dilute these colors than produce fawns and lilac cats. More on this later.
The chocolate and cinnamon Bengals are not recognized as standard colors in either TICA nor CFA and there are very few breeders that work with these genes.
“C” allele or color point series. These include the seal lynx point, seal sepia and seal mink. Color Points refer to darker coloration on the ears, nose and tail with markings that match that color. C- This is a cat with no color point. This is a dominant trait.
cs- is a cat that contains the Siamese gene (seal lynx point)
cb- is a cat that contains the Burmese gene (seal sepia tabby)
Note: this does not mean these traits came from the Siamese or Burmese breed. It refers to the fact that they are the same genes that are an influence in these breeds.
Combinations produce differently color pointed cats C/C is a cat that has no color points and carries no color point.
C/cs is a cat who carries seal lynx point meaning they do not express the color but when paired with another carrier or expressing cat with two copies of the gene they can produce a seal lynx
C/cb is a cat who carries seal sepia tabby meaning they do not express the color but when paired with another carrier or expressing cat with two copies of the gene they can produce a seal sepia Because the color points are recessive genes you must have two copies in order for the trait to present phenotypically (seen physically with the naked eye)
cs/cs is a seal lynx point
cb/cb is a seal sepia
Now in the color point series we have a co-dominant effect between cb (seal sepia) and cs (seal lynx). Co-dominant means that neither gene masks the other, no one is dominant or recessive, instead they express independently when separate as well as equally when together. This is what occurs in the mink tabby .We have a copy of cb and a copy of cs.
You cannot carry for seal mink. You need both components to create the color point type.
So just to review Dominant genes completely mask the recessive gene. The Recessive gene doesn't express unless paired with a second copy. Co-dominant is when two genes basically express equally AS WELL AS independently where as incomplete dominance occurs when one masks the other gene but not completely creating a new phenotype. “D” is the allele for Dilute or Color density. Dilute cats include the:
Blue (diluted from black) Lilac (diluted from chocolate)
Fawn (diluted from cinnamon) To be dilute, a cat must be d/d. It is recessive to D, the dominant allele which results in a non-diluted cat whether being homozygous or even just carrying one copy of d.
D/D is a non-dilute cat
D/d is a cat that carries dilute
d/d is a dilute cat
Although Blue is recognized by CFA it is not recognized by TICA. Lilac and Fawn are not recognized by TICA and in the Any Other Variety or AOV category by CFA. AOV traits cannot compete for titles in the show hall but they can be used in breeding programs and registered.
“E” Allele is the extension or “amber” gene. Most Bengals will get color test results back with E/E which represents a cat with black pigments. Whereas the “e” produces an increase in red pigments. It was thought to be the origin of the sorrel colored Bengals but this is no longer the assumption and unfortunately there is no further conclusions at this time.
Similarly there are a few breeders working with the Orange gene or Sex-Linked Red to produce what many refer to as the red bengal.
"O" Allele Orange is a unique gene as it is sex-linked found on the X chromosome. Females have two of the same sex chromosomes XX and males have an X and a Y gene. This gene is complex and expresses in various ways depending on the sex of the cat because of their sex chromosomes. Breeders must take extra steps to pair correctly to produce the desired kittens for their breeding program. The Orange gene is is denoted with O and is co-dominant where O codes for orange where as o codes for black/brown.
XOY- means the gene is located on the X sex chromosome resulting in an variation of orange color
XoY- means there is no Red gene and the cat is not expressing any orange color
XO/XO- means there is a copy of O on each sex chromosomes and expresses orange
Xo/Xo-means there are no copies of the dominant O so no orange is expressed
XO/Xo- means there is a copy of O on one of the X sex chromosomes but expresses as a tortoiseshell (a coat menagerie of black, red, orange, yellow, or cream). This is not an accepted color in any organization.
Finally, we have the I allele.
“I” Allele is the inhibitor allele. It operates by inhibiting pigment, primarily warm tones in part or completely. This is a dominant gene and represents the silver cats. A cat either is silver or it is not. As such a cat cannot carry the inhibitor gene/silver. I/I is a cat that is silver I/i is a cat that is silver i/i is a cat that is not silver Currently there is no genetic test for silver. We understand primarily how it works and expresses but where exactly on the chromosome it is located is still being discovered.
Click here for more on the Inhibitor gene
The Genetic Code
The genetic code is the genotype. These are the genetic traits that make up a cat. Some traits you can see outwardly such as color or pattern, some you cannot which means that either the cat doesn’t have those genes or they carry them and must be bred to another carrier or fully expressed cat for the offspring to have the traits expressed phenotypically.
A genotype is written out like a sentence. If you know what the individual traits and components mean you can easily read it.
If you color test your cat, the results will be in this order: A alleles E alleles
D alleles There currently is not a test for silver so the inhibitor gene (I) will be a guesstimate based on parentage and test pairings. While there are genetic tests for O, b1, b and e, we will not continue forward with them as they are extremely rare in the Bengal breed. We applaud the breeders that are working with these genes.
Once you familiarize yourself with what the alleles are, you can start putting them together to make a genotype.
Some of these alleles are located in different spots or locus on the chromosome (the structure that carries genetic information) and because of this we can have all sorts of combinations that results in different colors. Some of these combinations will change what you see on the outside or the phenotype. Think “P” physical = phenotype. The alternative is genotype or the actual genetics. “G” genetics = genotype.
Let's see what we get phenotypically from adjusting the A alleles. Our base cat just like the Asian Leopard Cats is genetically a Brown (Black) cat.
Let's adjust the C alleles or color point series and see how this changes the phenotype when we have carriers and fully expressing cats.
The same thing will result if we have a sepia carrier
If we add a fully expressed color point we start to see phenotype changes (in addition to the Charcoal Pattern Effect seen in the Agouti "A" Alleles.) First we have Seal Lynx (cs).
Then we have Seal Sepia (cb)
And finally Seal Mink (cb/cs)
Before we start combining more alleles than agouti and color point, let us take a step back and see how Agouti and Dilute interacts and changes the genotype and phenotype.
Above we see Dilute in a carrier status, now we look at a fully expressed Dilute.
Finally before diving in further, we explore the Inhibitor Gene unlike many of the other alleles, silver is dominant so I/i (heterozygous genotype) and I/I (homozygous genotype) express as Silver. Because we don't have a silver genetic test and can only determine heterozygosity or homozygosity through test pairing (determining genotype based on what parents produce in their offspring. If we breed a silver to a brown cat and any one kitten is non silver, then we know the silver parent(s) is/are heterozygous) Due to this effect of I/i and I/I expressing as Silver and not knowing (without test pairing or inferences from parents) from a test whether the cat is hetero/homozygous for Silver so we denote silver as I/-
Now lets add full expression of the color point genes
Let us dive even deeper into the world of color genetics. We have seen how Agouti looks when the A alleles change and what that looks like when we add color point, dilute or silver to those genotypes. Its time to combine. We know if we simply add a single copy of a recessive trait that the cat simply carries the trait, no phenotype changes occur. For example lets add a seal lynx and dilute carrier to our Agouti "A" alleles
The same thing occurs if we have a seal sepia and dilute carrier
However when we add two copies of a recessive trait the phenotype completely changes
We can't forget mink. Because one can not carry for mink it is not something we can visited in carrier status.
Now we can add Silver to our Agouti, Color Point and Dilute modifications. To make things fun we are going to use genotypes where color point and dilute are fully expressed (no carriers).
That is the basics of color genetics and how genotype, the genetic code, translates to phenotype, what we see physically expressed. Simple right? With a little practice, you'll get the hang of color genetics and it'll become second nature.