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Coat colours in cats
What are 'coat colours'?
photo's: © Margaret Henderson
In cats, as in most mammals, the pigmentary colours of coat and skin are very limited. There
is melanin in two forms: eumelanin that brings about the colours black and brown
(chocolate and cinnamon) and phaeomelanin producing colours between reddish brown and
pale orange brown. Then, responsible for the colour of the red blood cells, there is
haemoglobin that causes the pinkish colour of mucous membranes and of the non-melanin
parts of the skin.
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| black |
chocolate |
cinnamon |
red |
There are about ten pairs of genes involved in how and where both kinds of melanin are
produced. Apart from these there are several pairs of genes that determine the length and the
structure of hair and coat. All together they cause the phenotypic expression we call
'the colour' of our cat. At this moment DNA tests are only available for a limited number of
coat colour alleles.
The extension of the eumelanin in the coat is regulated by the agouti locus, the A-locus.
Animals with at least one dominant A-allele (AA- or Aa-animals) show a
'normal' (tabby) colour pattern in their coat. The meaning of the word normal here is: 'as
determined by the other colour genes'. The dominant, wild-type A-allele causes the agouti
shift phenomenon which causes hairs to be eumelanin pigmented at the tips and phaeomelanin
pigmented at the roots (revealing the underlying tabby pattern).
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black tabby blotched
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chocolate tabby spotted
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cinnamon tabby ticked
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red tabby mackerel
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Animals that are homozygous
for the recessive non-agouti or "hypermelanistic" a-allele (aa-animals) do not
produce a pattern in their coat nor the 'banding' in their hair; their coat will be 'self'
or 'solid'. The non-agouti genotype (aa) masks or hides the tabby pattern, although
sometimes a suggestion of the underlying pattern can be seen (called 'ghost pattern' or
'ghost marking').
The colour of the eumelanin in the coat and in the skin is determined by the
B-locus. There are at the moment three alleles known at the B-locus: in order of
dominance B > b > bl.
Animals with at least one B-allele will produce black eumelanin, the ones with at
least one b-allele (and no B-allele) will have chocolate eumelanin and the animals
that are homozygous for the most recessive bl-allele (blbl-animals)
will have cinnamon eumelanin in their coat and skin. Other colour genes determine where and how
much (black, chocolate or cinnamon) eumelanin is produced.
The restriction of melanin in the coat is regulated by the albino locus,
the C-locus. There are at the moment at least four, maybe five, alleles known at the
C-locus. Only three of them are relevant in DNA testing: in order of dominance
C > cb = cs.
Animals with at least one C-allele (full colour) will show a normal distribution
of their melanin. As before, the word normal means here 'as determined by the other colour
genes'.
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C-full colour
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cbcb burmese
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cbcs tonkinese
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cscs siamese
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The allele cb (Burmese) changes the black colour of eumelanin into dark
sepia or seal brown, the colour of the phaeomelanin changes to yellow. The points (nose, ears,
feet, tail) are usually darker than the body. The allele cs (Siamese)
restricts the dark sepia eumelanin to the points, the colour of the body fur is reduced to
light sepia or even to off-white. Animals that have both alleles cb and cs (so the cbcs-animals)
will show an intermediate colour between Burmese and Siamese, they are called Tonkinese.
Both alleles (cb and cs) have a variable temperature-
dependent expression. In a colder environment the colour of the animals develops into a darker
shade.
Finally there is the allele c that completely prevents the production of melanin.
Homozygous animals (cc) do not produce any melanin; they have a white coat and pink
eyes. As yet there is no DNA test to demonstrate the presence of the c allele.
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albino cat
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albino wallaby
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The distribution of pigment granules in the hair shaft is determined by the
dilution locus, the D-locus. Animals with at least one dominant allele (DD-
or Dd-animals) show a normal distribution of pigment granules in their hair. Animals
that are homozygous for the recessive 'dilution' allele (dd-animals) will have clumps
of coalesced pigment granules which causes a diluted looking coat colour. The dilution
changes the colour of the eumelanin as we see it (the phenotypical colour) from black into
blue (slate), from chocolate into lilac and from cinnamon into fawn. The colour of phaeomelanin
parts of the coat is changed from orange (yellowish brown) into cream.
DNA tests for coat colours
Breeds that can be tested
Breeding policy
Testing for coat colours
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