There are 3 versions of the full colour alleles: Black -
Chocolate - Sorrel. Black is also known as “Usual”, “Tawny”
or “Ruddy” in Abyssinians. Sorrel is also known as “Cinnamon” in many other breeds and countries.
The 3 versions or alleles operate as a hierarchy with Black
dominant to Chocolate and Sorrel, and Chocolate recessive
to Black but dominant to Sorrel. Sorrel is recessive to both
Black & Chocolate.
It’s useful to use the internationally recognised symbols for
individual genes. In the case of full colour the symbols are
B = Black version of the gene
b = Chocolate version of the gene
b1 = Sorrel version of the gene
A cat, male or female, may look Black (or Usual/Tawny/Ruddy)
– this is called its “phenotype” (fee-no-type) but genetically
is can be one of three types - its “genotype” (gee-no-type):
(a) BB - Black + Black
(b) Bb – Black + ‘carrying’ Chocolate
(c) Bb1 – Black + ‘carrying’ Sorrel
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The dominant gene takes over and shows in the coat colour.
The recessive gene is what they call "carried" in the cat
fancy, therefore a cat can be Black carrying Sorrel or Black
carrying Chocolate, but cannot carry both. An outwardly
Chocolate cat can have one of 2 different genotypes:
(d) bb – Chocolate + Chocolate
(e) bb1 – Chocolate + ‘carrying’ Sorrel
A Sorrel cat doesn't carry anything as it must by definition
have a Sorrel gene from both sire and dam.
(f) b1b1 – Sorrel + Sorrel
So if you mated a Chocolate carrying Sorrel to a Sorrel this
gives the chance of 50% Chocolate kittens and 50% Sorrel
kittens. The Chocolate kittens will all carry Sorrel.
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(e) SIRE
allele b |
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(e) SIRE allele b1 |
(f) DAM
allele b1 |
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Kitten bb1 Chocolate carrying Sorrel |
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Kitten b1b1
Sorrel |
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(f) DAM
allele b1 |
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Kitten bb1 Chocolate carrying Sorrel |
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Kitten b1b1
Sorrel |
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