Showing posts with label Genes. Show all posts
Showing posts with label Genes. Show all posts

Monday, 9 May 2022

Cat coats: solid-and-white - bicolor cats

black and white cat
Cat Coats Solid and White - Bicolor - photo copyright fofurasfelinas


This is another posting on cat coats. This time I discuss the impact of the white spotting gene on "solid" colored cats other than Tuxedo cats, which I have already discussed on this page. Tuxedo cats are very common and specific in their coat pattern so I've dealt with them separately. Both are bicolor cats meaning a cat coat of two colours, white and another solid colour.

Bicolour development - white spotting gene. Image: Sarah Hartwell.

The particular effect that the white spotting gene has on any one cat dictates the spread of white fur on the cat (or put it another way it restricts the spread of color). The cat fancy has given names to the patterns caused by this gene, which by the way is also called the piebald gene. It is considered a "semi-dominant" gene.

Bicolour faces white spotting gene. Image in public domain.

White spotted cats are one of the most common cats. The white spotting gene (represented by the letter "S" in the science of genetics) can change the appearance of any colored cat including tabby cats or tortoiseshell cats or a combination of the two (torbie). [See cat coats tortie and white]. When it affects a tortoiseshell cat, the cat is called a calico cat in the States.

Bicolours. The chart is by Sarah Hartwell of messybeast. Many thanks.

RELATED PAGE: White spotting gene charts.

A fine example of a cat with a solid and white coat is the Turkish Van (high grade spotting - see below). This has, of course, the "Van" pattern. Van is a town in the South east of Turkey, where the Turkish Van originally came from (including adjacent regions).

Another example of a well-known cat breed with a "solid and white coat" is the Japanese Bobtail. The Japanese Bobtail has a Bicolor pattern in both "solid and white" and calico (which is tortoiseshell and white mentioned above).

bicolor cat
Bicolor cat photo by tanakawho (this photographer is well known - see more of his work here plus the work of 2 other fine photographers). Picture reproduced here under a creative commons license.

I discuss, in brief, the workings of the piebald gene on the Tuxedo cat page as well as here. The effects of the piebald gene can be seen to varying degrees. The amount of white dictates whether the pattern is a grade 9 (almost total white with the colored fur limited to a few spots). This is called high grade spotting.

At the other end of the spectrum at grade 1 there is a very small amount of white. This is called low grade spotting. When the cat is low grade the genotype (genetic makeup in relation to the cat's coat) is normally heterozygous represented by the letters "Ss". Conversely when the coat is high grade (lots of white) a spotted cat is generally homozygous "SS".

Black and white bicolor Scottish Fold kitten from Russia (Siberia). Photo (excellent):  Анатолий Кузнецов.

The presence of the piebald gene results in white fur by causing special embryonic cells to behave in a defective manner. These cells are called "Melanoblasts" and they become the cells of the cats body that produce the granules of pigmentation that are embedded in the individual hairs. During the embryonic stage these cells migrate from the spine area. They fail to migrate properly and fully causing parts of the body to be without color. The wide variability of the effect of this gene is due, at least in part, to the presence of other unidentified genes called "polygenes".

The great Dr. Desmond Morris discusses bi-colour cats in his book Cat World. He tells us that such patterns are most common in non-pedigree cats. But of course, you will see this coat type in pedigree cats as well. It depends on the breed standard is to whether they are allowed or not. In the early days of the cat fancy the bi-colour cat was less likely to be accepted because they felt that they made a pure-bred animal look like a moggy.

This was prejudice against the coat but it was more likely to be accepted if there was some sort of distinguishing factors about the bicolour coat such as an attractive symmetry or the distribution of the colour was interesting.

In the early days of the cat fancy the black-and-white coat was referred to as a 'magpie cat'. And sometimes the bicolour cat is called a parti-colored cat. You will see "parti-colored" spelled in different ways. Apparently bicolour cats only attained championship status within the show cat fraternity in 1966.

You will see bicolour cats in longhaired and shorthaired cats and in many cat breeds such as the American Shorthair, British Shorthair, Devon Rex, Cornish Rex, Japanese bobtail, Maine Coon, Manx and Persians. These are just examples. There are others.

Here are some photographs of the solid and white coat pattern:

Cream and white - photo:
copyright Helmi Flick


Cat Coats Solid and White - Turkish Van - Photograph copyright Lazy_Lightning


Cat Coats Solid and White - Black and White Van pattern with a lot of white (grade 8 perhaps) - photograph copyright Helmi Flick.


Black with white (more than a Tuxedo). Photograph copyright Helmi Flick.



Cat Coats Solid and White - This is another black-and-white cat (hairless cat). This demonstrates how the white spotting gene affects the skin color as well. Perhaps more accurately it is the almost invisible downy hair strands near the skin which are pigmented.


Perhaps a more accurate description for this cat, a Sphynx Cat (or Sphynx-like cat) would be Black and Pink! Photograph copyright Helmi Flick.

Cat Coats Solid and White - Sources:
  • Beth Hicks
  • Messybeast - Sarah Hartwell

From Cat Coats Solid and White to Cat Facts

Wednesday, 18 August 2021

Is cat personality linked to coat colour and type?

People like to think that there is a connection between the appearance of someone or an animal and their personality. British people refer to tortoiseshell cats as being "naughty torties" or having "catitude". Sometimes blotched tabbies are referred to as "real homebodies". And mackerel tabbies are seen as being independent. While white patches on a cat's coat have a calming effect on the personality.

Incidentally, it is not until fairly recently that people started to understand that domestic cats have a personality. Even scientists believed that only humans had personalities. That seems hard to believe nowadays.

Is this tortie a naughty cat?
Is this tortie a naughty cat? Photo:Twitter.

I've always felt that red tabby cats have good relaxed characters. Red tabbies are also called ginger or marmalade cats. They always seem to be spoken of in glowing terms as companions with nice, affable characters. But this is all anecdotal. To turn to science, some scientists believe that the biochemistry that creates different coat colours and types also affects the cat's brain. This is called "pleiotropy". But apparently there is little evidence to support this scientific theory says Dr Bradshaw in Cat Sense.

Perhaps we are on a more solid scientific footing when we turn our attention to the purebred, pedigree cats. With pedigree cats there is a lineage so we know the parents and grandparents; in short, there is a family tree, which allows scientists to study the inheritance of the genes.

There is a relatively restricted gene pool in breeding lines which allows the temperament of a founding cat to be brought forward all the way down the breeding line. So, for example, there is a limited number of high-quality male cats within each breed who are available to produce the type of coat desired as per the breed standard. As a result, the personality of these tomcats becomes predominant within a section of all the cats in a single breed.

For example, there was a time about 20 years ago when British Shorthair cats bred in Scotland with tortoiseshell, cream and especially red coats were difficult to handle. They traced this personality trait back to a single male cat who had a difficult personality. This, incidentally, is an example of breeders breeding for appearance over personality. This founding, male cat was unsuitable, it seems.

And also pointed cats, which you will see both in the Siamese and other pedigree cats and indeed in non-pedigree cats, are likely to be vocal. This is a well-known trait for Siamese cats. The reason, it is said, is because the gene that causes the points i.e. the dark extremities to the cat's body are rare unless that cat has at least one Siamese in its recent ancestral past.

Another way in which coat type and colour can be linked to personality is when the gene that controls the coat is physically close, on the same chromosome, as the gene that affects the way the brain develops. Under these circumstances the chances that a kitten will inherit the combination of these two genes, one affecting the coat and one affecting the brain is much higher. They tend to be inherited together although it doesn't always happen.

An example would be the dominant white gene which causes a cat's coat to be devoid of pigment and therefore is white, sits next to a gene which causes both eyes to be blue and the cat to be deaf. That's why white cats are often deaf with blue eyes or they have odd-eye colour. Because the cat is deaf it affects their personality and therefore in this instance coat type and colour affects personality.

I am indebted to Dr John Bradshaw for the above. Some more...

One aspect of people attaching personality to coat type is that it may colour their opinion of their cat (excuse the pun). The point that I am getting at is that if a person believes that tortoiseshell cats are naughty and if with that belief, they mishandle their tortoiseshell cat and are scratched, the two aspects to their relationship come together which may result in the cat being relinquished to a shelter.

A study found that participants were likely to attribute friendliness to orange cats and intolerance to tricolour cats and aloofness to white and tricolour cats. White cats were seen as being more shy and calmer than cats of other colours.

The participants to the study said that they thought personality was more important than colour when selecting a cat companion. This is interesting because cat breeders of purebred cats attach more importance to appearance that personality. There appears to be a disconnect between cat breeders and their clients.

Monday, 31 May 2021

Sectoral heterochromia in an all-white cat

This is called sectoral heterochromia. It is rare and beautiful. No health issues. You do see it in domestic cats. The cat is all-white. It is the dominant white gene which affects eye pigmentation creation in the embryonic stage. It causes the removal of melanin pigment across a part of the iris. The blue color is caused by light refraction only (not blue pigment). The yellow by pigment (eumelanin). All-white cats have no pigment in the hair strands. This is why they can get sunburnt ears - no pigment to block sun and in any case the hairs are thin there.

The normal, most common, sort of heterochromia in cats is when they have odd-eyes. One eye is blue and the other is yellow normally. But there are various types of heterochromia and the one we see on this page is called sectoral heterochromia because each eye is divided up into two colours i.e. there are two sections to the eyes. Turkish Angoras sometimes have odd-eyes and they are favoured. They are often all-white cats too. The classic real Turkish Angora is all-white with odd-eye colour.

The cat below looks a bit like an Angora but is not to the best of my knowledge.

Sectoral heterochromia in an all-white cat
Sectoral heterochromia in an all-white cat. Photo: Reddit.com.

Monday, 14 September 2020

Agouti gene and tabby cat coat

The word "agouti" is rather confusing. It refers to a gene which creates a certain type of cat coat namely the tabby cat coat. It is signified by the symbol A. It is dominant. The recessive is non-agouti indicated by the symbol a. Dr Morris describes the word "agouti" as the name given to a coat in which each individual hair is marked with bands of black, brown and yellow. He is referring to the tabby coat in which each individual hair strand is banded, essentially striped. The striping is created by two types of colour pigment, eumelanin (black/brown pigment) and phaeomelanin (yellow/red pigment).

The toyger, a relatively rare cat breed has a striped tabby coat created by the agouti gene:

The glamorous Toyger has a tabby coat. Photos by Helmi Flick. Collage by Michael.

Tabby coats are marked with dark areas of swirling fur or stripes or spots. There is another version which is the ticked tabby, seen on the Abyssinian cat and also in another species of animal a large South American rodent called an agouti; hence the name. The Abyssinian cat is an all-agouti cat.

The agouti gene is very common and "highly conserved among all mammalian species". It produces a molecule called the "agouti protein". As the hair shaft grows within its hair follicle in the skin, eumelanin is produced by cells within the hair follicle called melanocytes. This pigment is deposited into the growing hair. As the amount of agouti protein increases within the melanocytes, eumelanin production is inhibited which results in a shift to production of phaeomelanin which is then deposited in the hair shaft to create this sandwich effect. In the ticked coat the band at the top is black with yellow at the base.

Another well-known animal that happens to be a cat but this time a wild cat species which has a very well-defined and strong ticked coat is the jaguarundi. The cat with the most pronounced ticked cat coat:

In short, when you think of the word agouti you should think of the tabby cat coat in all its varieties.

Note: the quote is from Robinson's Genetics.

Wednesday, 31 August 2011

Siamese cat phenotype frequency is 1 percent of stray cats

Defining the laboratory animal: IV Symposium, International Committee on ...(1971) says this about the Siamese cat. I quote verbatim and claim fair use as it is educational and I am referring to a small part of the text while promoting the work. (link to original page)

"Siamese on the other hand have been bred extensively. For instance, the gene frequency of the cat population at large in Paris (France) is 10 percent. That means phenotype frequency is 1 percent of that seen in stray cats. In Bangkok, the gene frequency is only 29 percent, and that is where they come from originally."

Some definitions:

gene frequency -- the frequency or proportion of genotypes in a population. "Genotype" means "the genetic makeup of a cell, an organism, or an individual".

phenotype frequency -- "an organism's observable characteristics or traits".

Siamese Cat Binocular Vision

The Siamese cat is well known for a squint and a kinked tail. Both have been bred out by breeders over the years as they are considered "defects" but they are nonetheless part of this cat breed's heritage. The kinked tail in cat show competition is reason to disqualify the cat as I recall.

There are colorful legends regarding the squint that are usually about Siamese cats who defended temples and valuables. The task was arduous and it caused the cats to develop a squint!

The question on some people's minds is, "does the Siamese cat squint affect normal vision and particularly binocular vision?" Let's first say that it isn't just Siamese cats that have squints but they have a genetic predisposition to acquiring the squint. The cat below is not a Siamese but has a clear squint. Perhaps she is a Siamese mix (lynx point)




Not Siamese but clear squint - Photo by fazen (Flickr)

Cats have two eyes to allow them to judge distance and depth. Two eyes give animals a form of three dimensional vision. This is important to cats in making judgements on tracking objects, jumping and hunting etc.

It transpires that the squint is apparently a compensation for defective wiring of the nerves that go from the eyes to the brain. In normal cats half the optical nerves cross over to the side of the brain opposite to the position of the eye. This provides binocular vision.

In Siamese cats the nerve fibres that were not meant to cross over, do in fact cross over. This causes "the faulty positioning of the retinal map on the tectum". The tectum is a region of the brain, specifically the dorsal part of the mesencephalon (midbrain). The squint cancels out the effects of the faulty positioning on the tectum by "altering the positioning of the retina".

So there you have it. The squint develops over the first six to eight weeks of the kitten's life to make this compensation.

Siamese cat binocular vision is maintained by the famous Siamese cat squint. That's how nature has compensated for a genetically inherited neurological defect. Incidentally, the Siamese and Persian cats have the most genetically inherited diseases and are two of the most long standing purebred cats.

The references are from the New Scientist Aug 17, 1972. Thanks to Google Books.

Tuesday, 26 July 2011

Dark Coated Siamese Cats

We know that Siamese cats have cream fur in the center of their body - the torso and upper part of the legs - while the extremities (points - strange word really) are darker. This is what makes the Siamese cat what it is.

Sometimes you see Siamese cats that have dark fur on their torso area. The contrast between the body and extremities is much reduced.

This occurs in older cats because of poor blood circulation. This results in the body being cooler which in turn leads to production of pigmentation in the skin that goes into the hair shafts.

I am guessing too that in cooler climates there might be darker fur in the torso area.

Monday, 25 July 2011

Siamese Cat Genetics

tThe bit about Siamese cat genetics that is particularly interesting is the way the pointing is created.

I'll occasionally quote Robinson's Genetics for Cat Breeders & Veterinarians if I may under fair use provisions. I am promoting the book.

"The phenotype is a form of 'Himalyan albinism'".

Production of the pigmentation that is in the hair strands depends on temperature. At a certain temperature (body temperature) the pigment is not produced while at the extremities where the skin is cooler it is.

"The albinism allele has other affects.." The visual pathway is disrupted". {see Siamese cat health}

"The seal point is a non-agouti black with the addition of the Siamese allele cs. The full genotype aaB-cscsD-. Note that Gloria Stephens in Legacy of the Cat  (page 19) says that "The genotype for a seal point shorthair is: a/a, B/-, D/-, i/i, L/-, s/s, T/-, wb/wb, w/w, cscs

Key: c=albino, cs=pointed, aa=non-agouti, B=Black, dd=dilution, D=dense pigmentation, O=red (Orange), o=non-orange. Click on this to see cat genetics symbols for more information.

The seal point is a degraded black typical of the workings of this allele.

The Blue pointed Siamese has the genotype: aaB-cscsdd.

The chocolate point Siamese has the genotype: aabbcscsD-

The lilac point has the genotype: aabbcscsdd.

The lynx point (tabby sometimes called Colorpoint Shorthair) has the genotype: A-B-cscsD-.

Blue tabby point is: A-B-cscsdd.

Blue tortie point is: aaB-cscsddOo.

Chocolate tabby point is: A-bb-cscsD-

Chocolate tortie point is: aabbcscsD-Oo.

Lilac tabby point is: A-bbcscsdd.

Lilac tortie point is: aabbcscsddOo.

Seal tortie point is: aaB-cscsD-Oo.

The seal tabby tortie is: A-B-cscsD-Oo.

All Siamese have the cscs.

The red point is: aacscsOO.

The red tabby point is: A-cscsOO.

This is not a complete list.

Thursday, 14 July 2011

Siamese Cat Gene Chart

Here is a Siamese cat gene chart courtesy Wikimedia Commons:

Siamese gene chart
Siamese cat gene chart

Make of this what you will! It is complicated. It is published under the Wikimedia license.

See this image in very large format on this page. This page makes the image readable.

Saturday, 23 February 2008

Cat Coats White

Cat coats white is the last in a series on the cat coats. See all the articles by clicking on this link. In previous articles I have mentioned the Piebald gene (White Spotting gene). The gene usually (denoted by the letter "S") produces coats with white "spots" although "spots" is a misleading term. It produces areas of white leaving other areas in a wide range of colors and patterns such as Tuxedo, Tabby, solid colors and others (it is perhaps best to see all the posting to get the complete picture). 

All-white Maine Coon
All-white Maine Coon



 As can be expected if the white spotting works to maximum effect, then the whole of the cat will be white instead of areas of white, either small or large. Accordingly, one of the three genes that produces all white cats is the white spotting gene. Its actions are wide ranging as can be seen. That's why it is said to have "variable expression". It is called "recessive white" sometimes and I suppose because of its variable actions, it is "semi-dominant". 

 The genes that produce white fur cover up the other colors. Note: Albino cats are due to a different effect, the lack of production of color (see below). 

The other gene that produces cat coats that are white is the dominant white gene ("W"). This gene masks all other colors. 

As a result, it is impossible by looking at the cat to see what other genes are present. To use technical language, the gene W is "epistatic" meaning it masks all other color genes. There may be an exception in relation to eye color. The dominant white gene is a simple non sex related dominant gene. The white cat is not due to the presence of a number of piebald (white spotting) genes. 

Russian-bred all-white British SH
Russian-bred all-white British Shorthair kitten. Photo: Альбина Шконда питомник британских кошек Golden Leris nursery Golden Leris. WCF.

The W gene is at a different position on the chromosome to the white spotting gene and is therefore independent of the white spotting gene. Epistatic crudely means that where there is a competition between genes as to what color or type of coat will be seen (for genes involved with coat color), the gene whose phenotype (the appearance) is expressed (the appearance seen) is said to be epistatic. 

The W gene is also associated with deafness as it can affect the cochlea in the inner ear (the fluid filled chamber that converts sound waves to nerve transmissions to the brain). The gene produces blue, orange or odd eyes. If the cat has blue eyes there is a good chance that he/she will be deaf as well. If she has one blue eye, there is a good chance that she will be deaf in the ear on the side of the blue eye. 

As the name of the gene implies this is a dominant gene so if fully present its effects are produced (from genotype - the genetics to phenotype - the physical result). In a survey of 185 cats, one quarter had normal hearing and yellow eyes, 31% had normal hearing and blue eyes, 7% were deaf and had yellow eyes and 37% were deaf and had blue eyes. 

 The third and highly unusual genetic make-up that results in all-white cat coats is the albino. This is complicated genetically so a brief mention is probably best. There are alleles that are known to produce albinism. 

An allele is one member of a pair of genes at a certain point on the chromosome. The alleles concerned are blue-eyes albino, pink eyes albino, Burmese Pattern, Siamese Pattern and full color (ref: Sarah Hartwell). These cats have pink eyes. The all-white cat is more prone to contract skin cancer as the skin more readily absorbs ultraviolet light. This should be born in mind by keepers of white cats in hot climates. Source:
  • Messybeast
  • Robinson's Genetics
  • Me

Featured Post

i hate cats

i hate cats, no i hate f**k**g cats is what some people say when they dislike cats. But they nearly always don't explain why. It appe...

Popular posts