The Co-Locus is a region of your dog's DNA which controls a brown/chocolate coat colour present in French Bulldogs known as cocoa. The cocoa colouring generally tends to be darker than the chocolate produced by the B-locus though this can vary depending on the combination of other colour genes.
Your dog can only be cocoa if they are also E/E or E/e on the E-Locus. The Co-Locus behaves in a similar way to the B-locus meaning you can have solid cocoa colour as we all, for example, cocoa and tan.
The cocoa colour is controlled by mutations on the HPS3 gene.
Your results will be reported as one combination of the I-locus alleles with the following interpretations.
|N/N||- no cocoa|
|N/co||- not cocoa - carrying cocoa|
Kiener S, Kehl A, Loechel R, Langbein-Detsch I, Müller E, Bannasch D, Jagannathan V, Leeb T. Novel Brown Coat Color (Cocoa) in French Bulldogs Results from a Nonsense Variant in HPS3. Genes (Basel). 2020 Jun 9;11(6):636. doi: 10.3390/genes11060636
Laukner A, Truchet L, Manukjan G, Schulze H, Langbein-Detsch I, Mueller E, Leeb T, Kehl A. Effects of Cocoa Genotypes on Coat Color, Platelets and Coagulation Parameters in French Bulldogs. Genes (Basel). 2021 Jul 19;12(7):1092