Blue Genetics- In Depth, Blue Bengal Group

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The Genetics of the Bengal

You can quickly learn the basics of the genetics that affect the coat of the Bengal cat.

However, before we get going, let me add one proviso. The research into cat genetics is continuing all of the time, and even in the last couple of years new genes have been identified. So if I am behind the times, or if you know more or better than I do, I would love to hear from you so that I can update this page.

This page mostly concentrates on coat type, colour and pattern. It does not cover all of the genes affecting the coat, but concentrates on those affecting the Bengal.

How Genes Work

The first thing to understand is that all genes come in pairs.

When an egg is formed it only contains one half of the pair of the dam’s genes – the other half of the pair goes into a different egg. Similarly, when sperm is formed, each only contains one half of the pair of the sire’s genes.

When the sperm fertilises the egg the two halfs join together to form a pair of genes again – so the kitten (other than in exceptional circumstances) always inherits half it’s genes from it’s dam and half from it’s sire.

It is not true that the sire’s genes are ‘stronger’ than the dam’s genes. After all, the sire inherited half his genes from his dam, and the dam inherited half her genes from her sire – so how can they be? Both the dam and sire should take equal credit for a ‘good’ kitten, and equal credit for a ‘bad’ kitten. It all depends on how the genes mix and match.

There are different genes that affect the pattern of the coat (spotted or marbled), and the colour of the coat (brown, snow, blue, silver, chocolate, cinnamon), and the type of coat (long or short haired). Each gene has a specific job to do.

Dominant and Recessive

Some genes are dominant and some are recessive.

The pair of genes could be made up of two dominant genes, or two recessive genes, or one of each. Where a cat has one dominant and one recessive gene as a pair, then the effect of the dominant gene will always display in the cat. The recessive gene will (usually) be invisible.

For example the spotted gene is dominant, and the marble gene is recessive. So if the pair of genes in a cat is made up from one spotted gene (dominant) and one marble gene (recessive) the cat will be spotted.

However, there are exceptions to this rule as some genes seem to be more ‘strongly’ dominant than others. This is usually described as being ‘incompletely dominant’.

The ‘Buzz Words’ – Homozygous and Heterozygous

Two very long words that have a simple meaning.

If a cat has a pair of genes of the same type then they are ‘Homozygous’. So a spotted cat, that has a pair of spotted genes is ‘Homozygous’.

If the cat has a pair of genes that are not the same, then they are ‘Heterozygous’.

For example, a spotted cat could have one spotted gene and one marble gene – this cat is Heterozygous. It appears to be spotted because the spotted gene is dominant to the marble gene.

Charting the Genes

A simple way to work out what kittens your cat might have, is to build a simple chart, and work out the combinations of genes.

Start by drawing a chart that is 3 boxes wide and 3 boxes deep. Ignore the top left hand box. Now fill in the the top row with the stud’s genes, and in the left hand column the queen’s genes.

In the example below, both the stud (at the top) and the queen (at the side) have one spotted gene and one marble gene.

Now take the gene from the left hand male box, and combine it with the top one from the female.

Now add the symbol from the left hand male box with the bottom one from the female.

Now do the same for the right hand two boxes.

You should end up with:

left, you have 2 spotted genes – this kitten will be spotted.

Top right, and bottom left – these two kittens will be spotted (the dominant gene), but carry the marble gene.

Bottom right- this kitten has two marble genes, so it will be a marble cat.

So the average that you would get from this mating are:

25% of the kittens are spotted, and do NOT carry marble

50% of the kittens are spotted and carry marble

25% of the kittens are marble

Remember though, that these are only averages. Some eggs may die before they are fertilised, some sperm may never get that far, and then fertilised eggs may not survive. And you never know which ones will actually go full term.

So don’t expect to always get one marble kitten in every litter of four where the parents are both spotted and carry marble. You have to repeat several matings before the ‘averages’ start to show up.

You can use this chart to work out the coat type, pattern or colour of any of the genes below – though the chart gets rather big and complicated if you try to chart more than one gene at a time – as you have to allow for every combination that might occur.

To work out the combinations of one gene, there are four possible combinations (the male carries a pair, and the female carries a pair). But to work out the combinations of two genes together (e.g. marbled or spotted, and snow or brown), there are sixteen possible combinations. As you might guess, the boxes get a bit big and complicated, and it is easy to lose track if you try to do too many combinations at a time.

Just as an example, here is a box where both the male and the female are brown spotted, but where they both carry marble and snow. Marble is recessive to spotting, and snow is recessive to brown.

So out of the mating of two brown spotteds who both carry marble and snow you would get (on average for 16 cats):

3 snow spotted, 2 of which carry marble

9 brown spotted - 2 carrying snow, 4 carrying snow and marble, 1 carrying marble and one homozygous

1 snow marble

3 brown marbles, 2 of which carry snow

Bengal Genes

These are the main genes that affect the Bengal, with an explanation of each of them. As said previously, research is still taking place and new genes are being discovered all the time, so if you know more, please let me know.

Others

Melanism- A mutation associated with the non-Agouti gene ‘a’

This causes the melanistic bengal – black spots on a black background

The Blue Combinations

Where you get a combination of dilute (the blue gene) and the other colour genes, you get the following. Where the name varies between TICA and the GCCF, both names are given.

Siamese gene (cs cs) with dilute (dd) is a Blue Seal Lynx Point (TICA) or Blue Blue-eyed Snow (GCCF)

Burmese gene (cb cb) with dilute (dd) is a Blue Seal Sepia (TICA) or Blue AOC Snow (GCCF)

Both snow genes (cs cb) with dilute (dd) is a Blue Seal Mink (TICA) or Blue AOC Snow (GCCF)

Silver (II or Ii) with dilute (dd) is the Blue Silver

Chocolate (bb) with dilute (dd) is a Lilac

Cinnamon (b1b1) with dilute (dd) is a Fawn

		MALE
		Spotted	Marbled
FEMALE	Spotted
	Marbled

		MALE
		Spotted	Marbled
FEMALE	Spotted	Spotted + Spotted
	Marbled

		MALE
		Spotted	Marbled
FEMALE	Spotted	Spotted + Spotted
	Marbled	Spotted + Marbled

		MALE
		Spotted	Marbled
FEMALE	Spotted	Spotted + Spotted	Marbled + Spotted
	Marbled	Spotted + Marbled

		MALE
		Spotted	Marbled
FEMALE	Spotted	Spotted + Spotted	Marbled + Spotted
	Marbled	Spotted + Marbled	Marbled + Marbled

		MALE
		Spotted	Marbled
FEMALE	Spotted	Spotted + Spotted	Marbled + Spotted
	Marbled	Spotted + Marbled	Marbled + Marbled

			MALE
		Spotted + snow	Marble + snow	Spotted + brown	Marble + brown
	Spotted + snow	2x spotted genes 2x snow genes= Snow spotted	1 spot + 1 marble 2x snow genes= Snow spotted	2x spotted genes 1 brown + 1 snow= Brown spotted	1 spot + 1 marble 1snow + 1 brown= Brown spotted
FEMALE	Marble + snow	1spot + 1 marble 2x snow= Snow spotted	2x marble 2x snow= Snow marble	1spot+ 1 marble 1 brown + 1 snow= Brown spotted	2x marble 1snow + 1 brown= Brown marble
	Spotted + brown	2x spotted 1 brown + 1 snow= Brown spotted	1 spot + 1 marble 1 brown + 1 snow Brown Spotted	2x spotted 2x brown= Brown spotted	1 spot + 1 marble 2x brown-= Brown spotted
	Marble + brown	1 marble + 1 spot 1 brown + 1 snow= Brown spotted	2x marble 1 brown + 1 snow= Brown marble	1 marble + 1 spot 2x brown= Brown spotted	2x marble 2x brown= Brown marble

Dominant	Recessive	Notes
A Agouti	a non-agouti	Agouti is the tabby/patterned cat Non-agouti is the self coloured (solid colour) cat A is dominant to a, though not always completely - you can sometimes see the shadow of the tabby pattern on a solid coloured black cat that is heterozygous (i.e. on one that is Aa) All Bengals are Agouti cats – preferably AA, though some cats may be Aa
B Black	b chocolate	B is incompletely dominant to b Bb can result in a black cat with rusty coloured shading b (chocolate) is incompletely dominant to b1 (cinnamon) These bengals have no black in their coat – all of the black is toned down to a rich chocolate This is the Chocolate Bengal
B Black	bl cinnamon	b1 is the cinnamon gene These bengals have no black in their coat – it is toned down to a rich cinnamon Where a cat has one chocolate gene and one cinnamon gene, the cat will tend to be a paler than normal shade of chocolate This is the Cinnamon Bengal
C Full colour	cs siamese	This is the ‘snow’ Bengal: Off-white/cream background, coloured points and blue eyes Note that reddish blue eyes may be a sign that this cat also carries chocolate TICA call this cat the Seal Lynx Point, the GCCF call it the Blue-eyed Snow
	cb burmese	Off-white/cream background, darker (sepia) coloured points, with gold or green eyes (seal sepia) TICA call this cat the Seal Sepia, the GCCF call it the AOC (any other eye colour) Snow
		If you have a Bengal that has one cs gene and one cb gene, then the two genes ‘mix’ – neither is dominant or recessive to one another. The result is a cat with turquoise eyes. This combination of genes is referred to as the ‘Tonkinese’ colour. TICA call this cat the Seal Mink, the GCCF do not differentiate between this cat and the ‘sepia’ and call it the AOC (any other eye colour) Snow
D Dense colour	d dilute colour	Dense colour is fully dominant to dilute colour. The dilute gene (d) dilutes the black to grey and the blue breeders usually selectively breed their cats to produce a deep blue/grey This is the Blue bengal
I Colour inhibitor	i normal colour	The standard description of the Inhibitor gene is that it is a completely dominant gene which inhibits all colour in the coat – i.e. causes the Silver Bengal. However, it appears to be either incompletely dominant, or is affected by rufousness – as we have all seen the ‘tarnished’ silver who has some hint of brown in the coat. A combination of Agouti (AA) with the inhibitor (I) causes smoke in some cases. Some believe that both the Inhibitor gene and the Agouti gene come in varying ‘strengths’, and that an excess of Inhibitor with insufficient Agouti causes the smoke. However, it is possible that other, as yet unidentified genes are coming into play.
L Short Hair	l long hair	The short haired gene is completely dominant to the long hair gene. The sources I have read say that ‘the length of hair is determined by selective breeding’ – however this comment in itself indicates that another gene (or genes) may be present which affect hair length – and the ‘selective breeding’ is selecting cats with this other ‘hair length modifier’ gene(s). The Bengal is a shorhaired cat (LL) The long haired variant of the Bengal is called the Cashmere.
Mc Vertical Flow	mb horizontal flow	Believed to cause the horizontal alignment of the marbled pattern found only in Bengals and believed to be inherited directly from the ALC
Mi not glittered	mi glittered	A ‘theoretical’ gene – causing the glitter on the Bengal coat. The designation of Mi is only ‘temporary’ – I have also seen this gene referred to as Gi or Gl. The colour of the glitter on Bengals varies depending on the ‘other’ colours of the coat. The brown bengal has a golden glitter, the snow has a ‘pearl’ glitter, the silver has a silver glitter, and the blue has a metallic blue glitter.
Rf Normal colour	rf rufous (? Or extension gene)	Originally thought to be a series of polygenes (blending genes), the rufous gene is now thought to be a separate gene that causes red in the coat. Another theory believes that the rufous colouring is caused by the ‘extension’ gene As the amount of red in a Bengal coat varies considerably from cat to cat, I am sure that most Bengal breeders will be convinced that this gene may come in varying ‘strengths’, or is affected by another gene that changes the amount of red in the coat.
S White spotting	s no white spotting	White spotting causes a ‘locket’ of white hair on the chest or tummy. This is not appropriate to the Bengal and should be bred out of the breed.
Sa Normal hair	sa satin/silk fur	Another ‘theoretical’ gene - No or minimal undercoat, with a satin finish to the coat It has been suggested that this gene is another or different cause for glitter (see Mi), however I think most Bengal breeders will agree that this is unlikely as Bengals that have silky fur with no undercoat are not always glittered, therefore it is likely that there are two separate genes causing the silky coat and the glitter..
Sp Pattern interrupt	sp normal tabby (Classic or Mackerel)	Recently identified as a separate gene affecting the tabby pattern by breaking up the pattern to cause spots rather than lines. It is still not known what causes the variance in spot shapes and colours (i.e. rosetting) The Toyger is another variant of the Bengal – the Toyger has stripes rather than spots, so the tabby marking is not ‘interrupted’
Wb Wide Band	wb normal band	Determines the width of the colour banding on a Ticked coat May be the cause of clear coats in the Bengal – believed to widen the Agouti band, and push the ticking off the end of the hair shaft.