B-Locus (chocolate/cinnamon)


The B-Locus is a region of your cat's DNA which controls whether your cat has a brown coat colour.

There are two alleles, or mutations, present in the B-locus which cause your cat's coat colour to be brown; b, and bl. If your cat has inherited any two of them with one coming from each parent then this will cause a brown coat to be expressed. The wild type black coat colour (B) is visible if no copies of b, or bl are present, or if only one copy of either b, or bl is present. If your cat only has one copy of b, or bl, then they carry brown and have the potential to produce brown kittens if mated with a brown or brown carrying cat. 

The black or brown colourations are caused by mutations on the TYRP1 gene. Brown is recessive meaning two copies of b are required to alter the black colouration to brown.


Your results will be reported as one combination of the B-locus alleles with the following interpretations.

B/B - black
B/b - black carrying chocolate
B/bl - black carrying cinnamon
b/b - chocolate
b/bl - chocolate carrying cinnamon
bl/bl - cinnamon


Scientific references:

Lyons LA, Foe IT, Rah HC, Grahn RA. Chocolate coated cats: TYRP1 mutations for brown color in domestic cats. Mamm Genome. 2005 May;16(5):356-66

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