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Dog Coat Color - Cocoa
| Acronym: | Cocoa |
| Gene: | HPS3 |
| Mutation: | c.2420G>A |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Coat color in dogs is an important characteristic along with hair length, growth pattern, and curl. Coat color is determined by the expression of two melanin pigments, eumelanin (black/brown) and pheomelanin (yellow/red). Brown or chocolate coat color in many dog breeds is frequently due to variants at the B locus or TYRP1 gene and few of those variants have been described so far. However, a different mutation has been detected to cause brown or „cocoa“ coat color in French Bulldogs – a variant within the HPS3 gene. HPS3 encodes a protein required for the correct biogenesis of lysosome-related organelles, including melanosomes, organelles that produce and store melanin. It is believed the lack of HPS3 causes melanosome biogenesis impairment, resulting in melanocytes that have a smaller than normal proportion of fully pigmented mature melanosomes which results in lighter coat color.
Cocoa color in French Bulldogs has a complex inheritance pattern, involving several genes, but the most important is the HSP3 gene. Mutation within that gene shows an autosomal recessive mode of inheritance meaning both mutated genes are required for the brown coat color to develop. However, due to the large number of different coat color alleles that segregate in French Bulldogs, it is often not possible to unambiguously determine what causes a specific phenotype in the dog. Genetic testing can identify carriers and help breeders in future mating pairs selection.
Results Reported As
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References:
Kiener, S., Kehl, A., Loechel, R., Langbein-Detsch, I., Müller, E., Bannasch, D., Jagannathan, V., Leeb, T. (2020). Novel Brown Coat Color (Cocoa) in French Bulldogs Results from a Nonsense Variant in HPS3. Genes, 11(6), 636. https://doi.org/10.3390/genes11060636
Laukner, A., Truchet, L., Manukjan, G., Schulze, H., Langbein-Detsch, I., Mueller, E., Leeb, T., Kehl, A. (2021). Effects of Cocoa Genotypes on Coat Color, Platelets and Coagulation Parameters in French Bulldogs. Genes, 12(7), 1092. https://doi.org/10.3390/genes12071092