B-locus (alleles: bd, bc, bs) (brown, chocolate, liver(nose))
B-locus (alleles: bd, bc, bs) (brown, chocolate, liver(nose))
General description
The B-locus can cause all black pigment to change to a brown colour. Common names for colours originating from the B-locus are: brown, chocolate, liver, red, etc.
Order details
| Test number | 8023 |
| Sample material | 0.5 ml EDTA blood, 2x cheek swab, 1x special swab (eNAT) |
| Test duration | 3-5 working days |
Test specifications
| Inheritance | Allelic series: B dominant over bd, bc, bs |
| Gene | TYRP1 |
| Literature | OMIA:001249-9615 |
Detailed description
Two alleles for the TYRP1-gene exist in dogs: the dominant full colour (B) and the recessive brown (b) which is also known in some breeds as liver, chocolate, sedge, and less frequently red.
Two copies of the b-allele are needed to vary black pigment to brown. For red or yellow dogs, the brown allele does not dilute the hair colour, but will change the colour of nose and foot pads from black to brown if two brown alleles (b/b) are present.There are three variants (bd, bc, bs) at the B locus known, which individually, as well as in combiantion with each other, can cause the modification of the pigment eumelanin in almost every breed.
Furthermore, there are three rare breed-specific variants (b4 (Australian Shepherd and Miniature American Shepherd), be (Lancashire Heeler), bh (Husky)) known to cause brown coat color, too (separate test).In the French Bulldog, the genetic cocoa variant can also, in addition to the B locus, cause a brown coat colour (separate test).
In some small dog breeds, the brown coat colour can in some certain cases not be explained by the known variants. Therefore, one or more additional variants at the B locus, or at another genetic locus, are likely to exist; these have not yet been characterised in detail and are therefore not detectable by a genetic test.
