Testing of dogs: Locus B canine

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Usual turnaround time: 12 business days
1 test price: 49.00 $ without VAT

Related tests

B Locus (Brown)

Result interpretation

For an overview of dog coat color hierarchy continue to the article Introduction into coat color in dogs.

The TYRP1 gene (Tyrosine related protein 1), located on canine chromosome 11, is responsible for the production of brown or black eumelanin. This gene has two alleles:

  • B – dominant, wild type allele (no mutation present), which causes the black coat colour. This means that the presence of only one B allele is sufficient to cause the black colouration of an individual (genotype B/B).

Individuals with the B allele have a black nose, black lips, and black mucous membrane pigmentation.

  • b – a recessive allele that is responsible for the brown colouration of the coat. The b allele has four variants:

An individual must carry two b alleles for the brown colour to be expressed (genotype b/b). Each of these alleles must be inherited from one parent. If he carries only one, then he is a carrier of the brown colour, and the coat colour will be black (genotype B/b).

Homozygotes b/b have brown to liver colouration of mucous membranes, nose and claws. They also tend to have lighter eye pigmentation. It is interesting to note that brown colouration is common in hunting dogs, where it serves as a camouflage when hunting game.

Dogs carrying the recessive genotype of locus E e/e and being b/b have a cream-coloured coat and brown mucous membranes, nose, and claws.

Another known allele of the B locus that we do not test for in the Genomia laboratory:

  • bh (NM_001194966.1, c.125G>A, p.Cys42Tyr) in exon 1 is responsible for the brown colour in huskies and their cross breeds

A French Bulldog may not carry any of the b alleles but will still show the dark brown (cocoa) coloration caused by the HPS3 gene mutation.


The picture shows an example of black (genotype E-B-D) and brown (genotype E-bb-D) Newfoundlander:

Black and brown Newfoundland dog


The B-locus test is suitable for most dog breeds, especially for: Australian Shepherd Dog, Border Collie, Epagneul Breton, Cardigan welsh corgi, Shar Pei, American Cocker Spaniel, Curly Coated Retriever, Dachshund, Dalmatian, Dobermann, English Cocker Spaniel, English Setter, English Springer Spaniel, Field Spaniel, Flat Coated Retriever, German Short-haired Pointing Dog, German Wire-haired Pointing Dog, Italian Greyhound, Labrador Retriever, Large Munsterlander, Lowchen, Caniche Miniature, Newfoundland, Pointer, Pomeranian, Portuguese Water Dog, Poodlepointer, Toy Poodle, Bohemian wire-haired Pointing griffon...

The test is not suitable for french bulldogs. Their brown color is caused by different gene variant, that has not been identified yet.


Result interpretation

Test for locus B consists from three different tests - three markers called BC, BD, BS.
There can be three different results in each marker:
(note: small letter "b" means presumption for brown color, big letter "B" means no brown color)

  • possible results for BC: Bc/Bc, Bc/bc (carrier of bc marker - the dog has Bc from one parent and bc from the other parent), bc/bc (brown color - the dog has bs from both parents)
  • possible results for BD: Bd/Bd, Bd/bd (carrier of bd marker - the dog has Bd from one parent and bd from the other parent), bd/bd (brown color - the dog has bs from both parents)
  • possible results for BS: Bs/Bs, Bs/bs (carrier of bs marker - the dog has Bs from one parent and bs from the other parent), bs/bs (brown color - the dog has bs from both parents)

What does it mean "bc,bd,bs" result ?

There is a problem. Without the parents we are not able to decide which marker was inherited from which parent.
Generally, there can be two possibilities:

1) the dog inherited all small "b" together from one parent
parent1: bc,bd,bs - first gene allele includes all b
parent2: Bc,Bd,Bs - second gene allele includes all B
Final locus B expression would be B/b - the dog will be carrier of brown, brown color will be hidden


2) the dog inherited some small "b" from one parent and some small "b" from the other parent - for example:
parent1: Bc,bd,bs - first gene allele includes some b
parent2: bc,Bd,Bs - second gene allele includes also some b
Finall locus B expression would be b/b - the dog will be brown colored (brown nose and coat)

So if result is bc,bd,bs - we are not able to decide which marker is inherited from which parent. Locus B sumarry result cannot be in such case formed as B/b or b/b.

Result report preview


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Usual turnaround time: 12 business days
1 test price: 49.00 $ without VAT