Dr. van Haeringen Laboratorium B.V.

H733 Coat Colour B-locus


During the last decades, a large number of scientific publications have described the genetic principles of coat colour and coat variation. Coat colours and coat variations are influenced by many hereditary factors. The DNA-tests are based on physiological effects in the body, in which the production and distribution of pigments result in many coat colour variants. In several cases, the coat colour of an animal may only be decided using DNA-tests.

The Tyrosinase-Related Protein 1 (TYRP1) gene, also known as Brown gene or B-Locus controls the dilution from black pigment to brown. The TYRP1 gene has no effect on the hair colour of dogs that are homozygous ee for the E-Locus as they do not have black pigment, but does have an effect on the colour of the nose and foot pads of these dogs. The Coat Colour B-Locus (H733) tests for the genetic status of the B-Locus. The B-Locus has four variants (alleles). The B allele is dominant and does not dilute the black pigment. From the recessive b allele three variants exist bs, bd and bc. All three variants of the recessive b allele have the same effect resulting in dilution of the black pigment into brown/chocolate/liver. Only when the dog has two copies of the recessive allele b (homozygous bb) the black pigment will be diluted to brown/chocolate/liver. For dogs that are red/yellow/cream and carry two copies of the recessive allele b the hair colour is not diluted but the colour of the nose and foot pads is changed from black to brown. In some breeds other mutations are present that cause chocolate colour that have not been identified yet. For example, the mutation for chocolate in French Bulldogs has not been found yet and the genetic basis is not known at this time

Test specific information

This test is also included in a Combination Package.

Since 2015, two brands have been developed. CombiGen® is mainly directed at veterinarian applications, whereas CombiBreed® is mainly directed at breeders and/or owners.
Detailed information about Coat Colours and Coat Variation is presented at www.combibreed.com.


Most coat colours and coat types are usually visible directly after birth.

Turn Around Time

The turn-around-time of a test depends to a large extent on the logistics of sample transportation to the laboratory. After receiving the sample at the test location, you can normally expect the result within 10 working days. A longer delivery time applies to tests carried out by a Partner Lab.

Location of disease or trait

Genetic factors influencing coat colours and coat types are usually visible on the outside of an individual. Several factors may be hidden by the external variation.

Breed dependence

For this test samples from all breeds are accepted.

Sample type

For this DNA test we accept the following materials: Blood EDTA, Swab, Blood Heparin, Tissue, Semen. Please contact Dr. Van Haeringen Laboratorium if you wish to submit other material as listed.


Coat colours and coat types are based on many genetic factors. For each factor, a separate test result will be returned.


Various genetic factors influencing coat colour and coat types are inherited in a dominant or recessive mode. Coat colours are influenced by a large number of genetic factors.

Severity of Disease

Genetic characteristics are not a disease.

Code H733

Coat Colour B-locus

€ 47,80 (Incl. 21% VAT)
€ 39,50 (Excl. VAT)