Bengal color genetics

The ABC's of Bengal Color Genetics
by Judi Richardson of RegalAir Bengals

Many people seem to be intimidated by color genetics, but this topic is actually not as difficult as it seems. Maybe if one were to think of it as a recipe for various flavors of ice cream, mixed drinks or a set of blueprints for building a Bengal, it would be easier to relate. I will try to condense, yet simplify the various color loci in feline genetics, as they relate to Bengals. Don't ever be afraid to ask questions. If the topic seems to be overwhelming and too difficult to relate to, just contact me privately and I will come up with a method that will work for you.

Terms and definitions:

Genotype= actual genetic makeup, AKA The genetic coding. EX. (A/a, B/B, C/C, D/d and etc)

Phenotype= what we SEE of the genetic makeup. Ex. A brown marble, silver spotted or etc.

Heterozygous= having two different copies of an allele. Ex (A/a)

Homozygous= having two identical copies of an allele. EX. (A/A)

?= unknown allele. Could be either dominant or recessive allele, would need to either do DNA testing or test breeding to determine the unknown allele.

Carrying= When a dominant allele also has a recessive allele tagging along on the gene pair (C,cs) it's said to be "carrying". EX. A brown spotted that carries for seal lynx point [SLP] and marble. Can't actually "see" the SLP or marble but they are there, in the genetic coding and may be passed onto offspring.

Dominant alleles ONLY need ONE copy to be "seen". Ex. (A/a)
Recessive alleles need TWO copies to be "seen". EX. (d/d)

Next, we will go over some genetic basics. Each color loci will contain a gene pair. One allele is provided by EACH parent and is written in order of dominance. Dominant genes (Capital letters) are listed first on down to the most recessive form. Ex. (A/a). Dominant genes may also be referred to as the "wild" genes.

"A" is for the Agouti loci.

Agouti means banded hair. The easiest example for me is a "wild" rabbit. One can readily see the different colored rings on each hair shaft when blowing into the fur. Bengal coats are so tight; it's difficult to blow into a Bengal coat to see the different colored bands on the hair shaft.

A= agouti and is the dominant form.
a= non-agouti and is the recessive form.

This recessive form also goes by several other names, so try not to be confused. All the terms are "politically correct". Non agouti is also known as; melanistic, self and solid.

**To date there are only two known alleles of agouti for color testing in Bengals. The current charcoal Bengal study is researching to find the gene(s) responsible for "charcoal". It has been theorized that it may be caused by an intermediate agouti gene—some are calling "A1". It may also be polygenic, which simply means more than one gene or color loci may be involved in creating the "charcoal" coloring. Hopefully, in the near future science will prove and provide the pieces of this color question.


"B" is for Brown loci.

B= Brown AKA Full brown

b= chocolate (recessive to brown but more dominant than cinnamon)

b1= cinnamon

 

"C" is for Colorpoint Restriction loci.

Colorpoint restriction works with melanin and how/where it is distributed on the cat. Think body parts that would become colder the quickest—ears, nose, face, feet and tail.

C= Full color

cb= Burmese AKA sepia

cs= Siamese AKA seal lynx point

c= Albino (VERY, VERY rarely seen in Bengals)

**Mink isn't a single color allele (which is why it isn't a choice above). Mink is created when a cat has ONE copy of Burmese <cb> and ONE copy of Siamese <cs>, as it is an intermediate color that is the co-dominace of the two together (cb/cs). Maybe think of them as primary colors in the color wheel. Burmese <cb> as "blue" and the Siamese <cs> as "yellow"—it takes the two shared together to make mink (cb/cs) or "green".

 

"D" is for Dilution or Dense color loci

Dilution is where the pigment is "diluted" down to lighter colors.

D= Full color or Dense color

d= Dilution AKA Blue gene

EX. Black is diluted to blue, chocolate diluted to lilac and etc.


"E" is for Amber loci

This doesn't appear to affect Bengals. On the UC Davis color panel test, it states it's for Norweigen Forest Cats.

E= Full color

e= Amber gene

 

"N" is for Gloved loci

Not seen in Bengals, but Birmans that we would say have "mittens".

N= Normal, not gloved

G= Gloved

**Odd that they would choose to break tradition and use a different letter and a capital letter at that, to depict gloved and not gloved. But this is how the UC Davis test will read.

 

 

Now let's discuss silver Bengals. Silvers are created by the Inhibitor gene (I/?), as it inhibits (not eliminates) warm pigment. The Inhibitor gene is dominant, hence it ONLY requires ONE copy to create a silver. This also means that in order for a cat to be silver it MUST have at least one silver parent. The Inhibitor gene can NOT be "carried". A cat is either a silver or it isn't. Currently there isn't a commercial color test for the Inhibitor gene but it would be like this.

I= Inhibitor AKA silver
i= non-inhibitor or non-silver

**A cat with TWO copies of the Inhibitor allele (I/I) should have less tarnish coming thru due to "double dose" of warm pigment Inhibitor.
Now we put all this "alphabet soup", the "recipe" or "blueprints" to work. Every cat has its genetic code that states what the cat will look like and what genes it may carry.

All the following genetic codes (genotype) are for brown Bengals, but they may each be carrying a different recessive gene, somewhere in the code. But they will all "look" brown (have a brown phenotype). **Since the only UC Davis color codes that appear to be affecting Bengals are "A-D" those are the ones we will concentrate on.

A/A B/B C/C D/D
A/a B/B C/C D/D
A/A B/b C/C D/D
A/A B/b1 C/C D/D
A/A B/B C/cb D/D
A/A B/B C/cs D/D
A/A B/B C/C D/d

If ANY of the above codes also had the Inhibitor gene present (I/i), then those cats would all "look" silver (have a silver phenotype).

 

By simply changing a letter (allele) in the genetic code, it changes what genes that cat has & can pass on to its offspring.

Remember it takes TWO recessive alleles (letters) on ONE loci in order for that recessive color to be seen.

Here are a few examples:

A/A B/B cb/cs D/D This would be a seal mink.

A/A B/B cs/cs d/d This would be a blue lynx point

a/a B/B C/C D/D This would be a non-agouti AKA melanistic, self or solid Bengal.

A/A b/b C/C D/D This would be a chocolate.

In conclusion, recessive alleles require TWO copies to be "seen", whereas dominant alleles only need ONE copy to "look" that color. Dominant colors may carry recessive alleles for several generations before they pair up with another recessive allele and seem to "pop up" out of the blue.

Now when one hears someone incorrectly state, "my kittens carry for silver" or "my kittens carry for mink" you will know that is not possible and can hopefully educate them why those statements are incorrect.  Hope this sparks interest in learning more about feline genetics. Remember, the only "dumb" question, is the one that wasn't asked. I am always happy to discuss Bengals, health or color genetics. Please feel free to contact me anytime.

Judi Richardson
RegalAir Bengals
RegalAir_Bengals@yahoo.com

 

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