Chocolate coat colour

About the Colour

A mutation in the Brown gene (tyrosinase-related protein-1, TYRP1) results in the Chocolate coat colour.

The B allele is wild-type and produces a normal colouration, the b allele produces a chocolate colouration. The mutation is recessive, hence two copies of the b allele are required for chocolate colouration.

Interpretation of results

Test Result Interpretation
Chocolate (b/b) Has two copies of the Chocolate allele (b/b)
Cat is Chocolate
Carrier of Chocolate (B/b) Has one copy of the Chocolate allele (B/b)
Full colour or possibly Chocolate if the cat also carries Cinnamon
Does not carry Chocolate (B/B, B/bl or bl/bl) Has no copies of the Chocolate allele (B/B, B/bl or bl/bl)
Full colour or possibly Cinnamon

 

FAQs

How do I test for Lilac in my Ragdolls?

Lilac is the result of the Dilute gene working on the Chocolate gene.

The results must be Chocolate (b/b) and Dilute (d/d) for the Ragdoll to be Lilac.

 

How do I test for Lilac in my British Shorthairs?

Lilac is the result of the Dilute gene working on the Chocolate or Chocolate and Cinnamon genes.

The results must be Chocolate (b/b) and Dilute (d/d) or Chocolate carrying Cinnamon (b/bI) and Dilute (d/d) for the British Shorthair to be Lilac.

 

The genetics of Chocolate, Cinnamon and Dilute colours

The Brown gene

The Brown gene has three alleles (B, b and bI), with B dominant to b, and b dominant to bI. When B is present (BB, Bb or BbI) the coat colour is its normal, full colour. If a cat is bb or bbI the brown is lightened to chocolate. When a cat is bI bI the colour is further lightened to cinnamon.

The Dilute gene

The Dilute gene has two alleles (D and d), with D dominant to d. When D is present (DD or Dd) the coat colour is not diluted. If a cat is dd the coat colour is diluted:

Black is diluted to Blue

Chocolate is diluted to Lilac

Cinnamon is diluted to Fawn

Red is diluted to Cream

Chocolate, Cinnamon and Dilute Colours

Chocolate/Cinnamon Dilute Coat colour
BB or Bb or BbI DD or Dd Black/Brown
BB or Bb or BbI dd Blue
bb or bbI DD or Dd Chocolate
bb or bbI dd Lilac
bIbI DD or Dd Cinnamon
bIbI dd Fawn

 

Further information

View and print 'Genetic tests for cats: what the practitioner needs to know' from our Feline Update Archive

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