Coat colour Cocoa / dark chocolate (HPS3-related) - French Bulldog

What does this test examine?

This DNA test detects the HPS3 c.2420G>A variant that causes recessive Cocoa coat colour in the French Bulldog. Cocoa is also described as dark chocolate, Co locus, HPS3-related brown coat colour and, in breeding language, the former non-testable chocolate.

What does Cocoa mean?

Most brown coat colour in dogs is explained by the B locus/TYRP1. Cocoa is different: it is caused by a recessive variant in HPS3. Dogs with two cocoa alleles may show a brown to dark chocolate coat. The colour can darken with age and the final shade also depends on other loci such as B, D, E, A and K.

Cocoa can also affect pigment in nose, skin and foot pads. In some dogs the difference from other brown variants is subtle, which makes DNA testing more reliable than visual assessment alone.

Inheritance and result

Cocoa is autosomal recessive. A dog with one copy is a carrier and usually does not show the cocoa colour. A dog with two copies is genetically cocoa and can express the colour depending on the rest of the coat-colour genotype.

• N/N: cocoa variant not detected.
• N/co: carrier of cocoa; can pass the allele on.
• co/co: genetically cocoa; this genotype causes cocoa/dark chocolate pigmentation when the genetic background allows expression.

Practical value of this test

This test is very useful for French Bulldog breeders who want to distinguish chocolate and cocoa lines correctly. The result shows whether a dog carries the HPS3 cocoa variant, whether it can express cocoa and how likely offspring are to inherit the allele.

• Helps distinguish cocoa from TYRP1/B-locus brown.
• Reveals hidden carriers before matings are planned.
• Supports planning of cocoa, chocolate, lilac and related colour combinations.
• Provides clearer information for purchase, sale and puppy colour expectations.
• Supports genetic confirmation of colour claims rather than visual assessment alone.