Zoolyx NV

H820 Coat Colour A-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 Agouti gene (ASIP gene) is responsible for the production of a protein that regulates the distribution of black pigment (eumelanin) within the hair shaft. This gene is also known as the A-locus and determines whether an animal expresses an agouti appearance, and if so what type, by controlling the distribution of pigment in individual hairs. The agouti pattern can be seen in both black-based and red-based colours. The coat colour is further complicated by the interaction with the K-locus and the E-locus. The agouti pattern is only expressed if on the K-locus no copy of the KB allele is present in combination with at least one copy of the E or Em allele on the E-locus. The Coat Colour A-Locus test (H820) tests for the genetic status of the A-locus. The A-locus has four variants (alleles). The most dominant allele is Ay, followed by aw, then at, then a. The dominant Ay allele produces a sable or fawn coat colour. The allele aw produces a colour known as wild sable or wild type. With this colouration, the hairs switch pigmentation from black to reddish or fawn. This colour is sometimes seen in German Shepherds and other shepherd breeds. The allele at results in tan points (tan markings on a dark dog) and produces black-and-tan and tricolour dogs. A tricolour dog is black-and-tan plus white. The allele a is also called the recessive black allele and results in a solid black/brown/blue/lilac or bicolour dog. Some breeds are fixed for only one variant. The Norwegian Elkhound is fixed for the aw allele and the Beagle is fixed for the at allele. In many breeds 2 or 3 alleles are present.

Test specific information

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.

Turnaround time

The Turnaround Time (TAT) depends on various factors, such as the shipment time of your sample to the test location, the test method(s) and whether the tests are performed completely or partially by a Partner Lab or Patent owner.

The TAT of tests performed at our facilities is normally 10 working days after receipt of the sample at the testing laboratory (VHL, VHP or Certagen). For tests performed by a Partner Laboratory (so-called "partner lab test") or patent owner, the TAT is at least 20 working days after receipt of your sample. Because the shipment time to our Partner Labs or patent owner may vary due to factors we cannot influence, the mentioned 20 working days are therefore an estimate.

Sometimes it is necessary to re-run your sample. We call this a retest. In that case, the TAT will of course be extended.

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, Blood Heparin, Swab, Semen, Tissue. 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


Code H820

Coat Colour A-locus

€ 50,94 (Incl. 21% VAT)
€ 42,10 (Excl. VAT)