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Cocoa mutation in French Bulldogs

A mutation has been identified that is responsible for the brown color seen in many French Bulldogs that is known amongst breeders as “untestable chocolate.” These dogs do not derive their color from any of the known “b” chocolate or liver mutations that are recessive alleles at the B locus. This new mutation is located in a different gene. Therefore, we are calling the mutation cocoa so as not to confuse it with the previously testable forms of chocolate. This is the same gene that harbors a mutation responsible for cocoa mice.

The mutation was identified by way of whole genome sequencing in two “untestable chocolate” French Bulldogs. Follow up genotyping of research samples from untestable chocolates and carriers verified that the test we developed can identify dogs that are clear, carrier, or have two copies of the cocoa mutation. The original research paper can be found here:

It is important to note that this test is for a single mutation. We expect it to identify the lion’s share of cocoa alleles, but there will be some outliers. Just like with the B locus and D locus where follow up research identified second, third and fourth mutations years later, the same may happen here.

We expect nearly all lilac, lilac fawn, lilac brindle and lilac merle dogs to have two copies of this mutation. There may be some, however, that are lilac due to the B locus.

Result Types

0 copies (does not carry cocoa)
1 copy (carries cocoa)
2 copies (cocoa)

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