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 white spotting patterns that occur in many dog breeds do not have a uniform genetic basis. The Microphthalmia Associated Transcription Factor gene (MITF gene) is associated with many white spotting patterns. This gene is also known as the S-Locus. There are three major white spotting patterns described. One pattern is called “Irish spotting” and is a symmetrical pattern with white markings on the undersides, collar and muzzle, and/or blaze as demonstrated by breeds such as the Boston Terrier, Corgi, Bernese Mountain dog and Basenji. Another pattern of less symmetrical white spotting in which random white spots occur on the body of the dog is often called piebald, parti or random white and is observed in several breeds, including the Beagle and Fox Terrier. The third major pattern is called extreme white and results in a dog that is almost entirely white but usually has at least some color on the head. Furthermore, there is a pattern called mantle, this pattern is similar to Irish spotting but with more white extending onto the thigh and up the torso, as seen in some Great Danes. Another pattern that is similar to Irish spotting is called flash or pseudo-Irish and occurs in Boxers.
A mutation found in the MITF gene is associated with the piebald spotting pattern in more than 25 different dog breeds. The Coat Colour Piebald test (H326) tests for the genetic status of this mutation. It results in two variants (alleles). The allele N does not produce a piebald pattern, therefor dogs with two copies of the N allele do not display the piebald pattern. The allele S is associated with the piebald pattern, however the amount of white spotting expressed varies from breed to breed and among individuals within a breed. In many breeds such as Collie, Great Dane, Italian Greyhound, Shetland Sheepdog, Boxer and Bull Terrier, piebald behaves as a dosage-dependent trait. In those breeds the allele S is semi-dominant. One copy of the S allele (S/N) results in a limited white spotting pattern. Dogs with two copies of the S allele (S/S) display more extreme white with colour only on the head and perhaps a body spot. In Boxers and Bull Terriers, dogs that have two copies of the S allele (S/S) are completely white while dogs that only have one copy of the S allele (N/S) display the mantle pattern (called flash in these breeds). However, additional mutations in MITF or other white-spotting genes that affect the amount of white being expressed appear to be present in these breeds. In some other breeds, the allele S is recessive and in those breeds two copies are needed to produce the piebald pattern.
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.
Symptoms will develop at a young age. Within a few hours to a maximum of several weeks after birth, the characteristics that go with these genetic effects will become visible.
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.
For this test samples from all breeds are accepted.
For this DNA test we accept the following materials: Tissue, Swab, Semen, Blood EDTA, Blood Heparin. 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
Factors influencing coat colour and coat types are usually not related to diseases.