Dog

The E locus or extension refers to a mutation in the MC1R gene. For this test code, the mutation being tested is the e^2 mutation. In the Australian Cattle Dog, dogs with two copies of the e^1 or e^2 alleles or one copy of each allele will have a cream coat. For the e^1 allele and other breeds, see the following link: DOG-LOCUS-E.

Locus Em or melanin mask causes the black mask on the dog's face. This allele is dominant because only one copy is needed to express the mask phenotype. The mask can be tested for in any breed, but is most commonly found in the breeds listed below.

Locus K or dominant black has 3 variants KB, Kbr and ky. The KB allele prevents the expression of the A or agouti locus, the coat colour is then determined by the B and E locus. The coat colour of dogs that are ky/ky will be determined by the A locus. The Kbr variant is responsible for the brindle coat but the mutation has not yet been identified.

The locus D or dilution refers to a mutation in the MLPH gene that causes a diluted coat colour. This mutation dilutes black to blue, chocolate to lilac and yellow to champagne. The mutation tested is the d^1 mutation. For the breeds Chow Chow, Sloughi and Thai Ridgeback, the test to be performed is the DOG-LOCUS-D-CHOW test.

Locus S identifies piebald/white spotting patterns in dogs. A particular mutation within the MITF gene is linked to piebald spotting, though its impact varies across breeds. In breeds such as Collies and Boxers, this mutation exhibits dosage-dependent effects, where one copy produces partial white patterns and two copies result in more extensive white. Conversely, in other breeds, piebald spotting follows a recessive pattern, necessitating two copies for manifestation.

The locus D or dilution refers to a mutation in the MLPH gene that causes a diluted coat colour. This mutation dilutes black to blue, chocolate to lilac and yellow to champagne. The mutation tested is the d^2 mutation and is specific to the Chow Chow, Sloughi and Thai Ridgeback breeds. For the other breeds, the test to be performed is the DOG-LOCUS-D test.

Locus I determines a dilution of the pheomelanin pigments (red or yellow pigment), resulting in a dilution of the fawn coat to cream, sand or white depending on the breed. The mutation does not affect the eumelanin pigments and therefore has no impact on the black or brown coat.

The Merle gene creates patches of colour in the coat and blue or odd-coloured eyes. Merle dogs may have hearing and eye problems. Dogs homozygous for Merle, also known as double Merle, are predominantly white and prone to several health problems. Merle can be tested in any breed, but is most often found in the breeds listed below.

The mutation responsible for the cocoa colour in the French bulldog has been identified in the Hermansky-Pudlak syndrome 3 (HPS3) gene. Dogs homozygous for this mutation are a shade darker brown than dogs mutated for brown (Locus B).  In humans and mice, mutations in the HPS3 gene are associated with symptoms such as visual impairment, abnormal eye pigmentation and bleeding. These effects of the mutation have not been reported in dogs homozygous for the cocoa variant. ogs with two copies of the cocoa variant can be cocoa, however the final colour of the dog also depends on other genes controlling coat colour.  

The curly coat is caused by a mutation in the Keratin-71 (KRT71) gene. The test can be performed for any breed but is particularly relevant for the following breeds: Airedale Terrier, Bichon Frise, Havanese, Maltese, Border Collie, Chesapeake Bay Retriever, Chihuahua, Dachshund, Leonberger, Portuguese Water Dog, Welsh Terrier, Wire Fox Terrier. This test is not valid for the Golden Retriever.