Chromosomes of a Brown Great Dane
There are many genetic variations in the brown Great Dane. Some of these variations are common to all Danes. The M and H loci are two examples. Another variation is called the d-series. The ASIP gene is also common. Almost all dogs have both the H and M loci.
In order to produce a brown dog, it’s necessary to have a brown gene in the dog’s DNA. There are two eumelanin diluter genes in dogs: one is called the blue diluter gene and the other is known as the brown gene. The brown gene is present on chromosome 11 and is responsible for producing the brown color in a dog. This gene can be either dominant or recessive.
A Great Dane with black spots is a harlequin. A harlequin Dane is genetically merle. Merles have diluted pigment areas, while blacks have a full-pigmented coat. In contrast, a merle dog has a base coat that is white. The merle gene is absent in blacks.
While the fawn color is associated with fawn Great Danes, this color is not present in all breeds. In order to exhibit fawn, a Great Dane must have two copies of the B/B allele. It’s important to note that a ky/ky genotype is not present in all standard Danes, but it is expected to be available soon.
In some cases, the brown gene is absent in a dog, causing a brown-dilute coat color. This pigmentation problem does not result in defects in the dog’s coat, although it does weaken the structures of the dog’s body.
Merle phenotype is a hereditary disorder characterized by two or more overlapping alleles at the M locus.’m’ stands for wt allele that is responsible for normal pigmentation while ‘M’ denotes the presence of the Merle variant in any form. Merle is an incompletely dominant autosomal trait and occurs in both heterozygous and homozygous dogs. In heterozygous dogs, the phenotype is milder than in homozygous Merle dogs. However, homozygous Merle dogs have three copies of the SINE insertion in their chromosomes. As a result, these dogs are called ‘double Merle’ or ‘pure white’.
Geneticist Clarence Little defined the coat colour phenotypes of dogs and assigned each colour to a particular gene (locus). He identified loci and named them after the phenotypes they attributed to them. The kbr allele is more often found in fawn and black dogs, while wt ky is present in tan-coloured dogs.
The dominant MC1R allele causes localised synthesis of eumelanin, which appears on the muzzle of certain dogs. This phenotype is not visible on a dog with a black coat, but may be present in a black dog that turns grey. The masked allele is caused by a missense variant at the c.790A>G gene that results in a change of one amino acid from methionine to valine.
Dogs with extreme white genotypes are almost completely white, but others have a typical piebald pattern, with patches of white pigmentation remaining. This high degree of individual variability indicates that other modifier genes may also play a role in the development of this gene’s phenotype.
The H locus of a Brown Great Danie has three alleles that determine its color. The dominant black allele reduces the expression of the A locus and only requires one copy to produce a solid black dog. The “brindling” allele is written Kbr and causes a dog’s coat to have alternating stripes of phaeomelanin and eumelanin. The “brindling” allele has a recessive effect on the dominant black allele.
The H locus is homozygous in a Brown Great Dane if its coat is fully pigmented. A dog that lacks this gene will have a pale gold coat. A dog with both haplozygosity and a recessive gene will be blue or grey.
MC1R is a gene located on the chromosome 5 of canines. The gene carries three alleles, two of which are dominant and one is recessive. The dominant allele causes the dog’s fur to be dark, while the recessive allele results in a dog that lacks dark pigment. However, this gene is not present in all Great Danes.
MC1R is the first gene studied in dogs. The gene was discovered to be in the CFA5 region, six centimeters from the ZuBeCa6 gene. In 2000, Newton et al. published their findings. The mutation 914C-T causes the clear red coat colour of a dog and results in premature stop codon (R306ter). In 2002, Schmutz and colleagues studied a large number of breeds to identify the wild type allele.
In the WHTC dataset of canine ASIP genotypes, the Great Dane, Anatolian Shepherd, Tibetan Mastiff, and Tibetan Spaniel are all included. The WHTC database also includes a minimum of ten breeds that contain the positive aw allele and at least two ASIP variant alleles in any single dog. When reporting genotypes, commercial laboratories should include a disclaimer.
In mice, the ASIP gene has a dorsal and ventral promoter region, which differs from the promoter region in dogs. In dogs, the promoters of ASIP have yet to be identified. As a result, the phenotype of the ASIP gene is not consistent among all individuals and breeds.
The A3+ allele is a result of a partial ASIP duplication, characterized by the presence of two adjacent SINE alleles. These alleles are usually bi-allelic and have no phenotype impact. If a functional duplication is the culprit, assays designed to amplify genomic regions could identify functional ASIP copies. However, this type of duplication would be variable in the number and frequency of allele variants.
However, the current ASIP gene approach has been working well in many breeds. However, data from several breeds suggests that it is incorrectly interpreted in several breeds. Therefore, the terminology of wild-type aw should be replaced with haplotype, where the presence of a variant allele at loci is associated with a distinct color phenotype. This change should also be made to existing allele hierarchy methodologies.
Brown Great Danes may have a variety of coat patterns and colors. For example, some have black spots while others have white spots. They may have a harlequin pattern, which is an intriguing color variation. Another variation is a merle coat, which has black and white spots. This coat pattern can help a dog mask its shortness.
This type of pattern is caused by a low phaeomelanin concentration on the underside of the dog’s coat. The resulting color is often beige, or almost white. Over time, the pattern may become less distinct and blend into the rest of the dog’s red coat. While this color blending is not as dramatic as in other patterns, it can be easily identified by its distinct contrast.
This coat color pattern is also called a tiger stripe. This color pattern is characterized by dark stripes across the body, including the nose. The striped pattern is often referred to as “tiger-striped.” Its pattern is most striking in brindled Great Danes, as the striped appearance is quite eye-catching.
Another brown color variation of a brown Great Dane is the fawn color. This pattern is distinguished by the muzzle and the coat. This color pattern is caused by a combination of two different types of Great Danes, which are both black and brown. Both of these colors are rare.
There are two alleles that contribute to the harlequin coat pattern in Great Danes. The harlequin pattern is characterized by ragged patches of full color on a white background. It is a bigenic trait that results from the interaction of the dominant modifier locus, H, and the merle allele of the SILV gene. It is unclear what causes this pattern, but recent research indicates that the gene is embryonic recessive lethal. Although there is no genetic test available for this locus yet, researchers believe that the test will be available in the near future.
The A locus determines the type of pigment, which is produced in a Great Dane. The MC1R gene is responsible for producing fawn, sable, and tan point Great Danes. The Ay allele affects the switching of red pigment to black pigment. Most Great Danes have fawn/sable coats. Fawn is the dominant color, which ranges from a reddish fawn to a black fawn. Fawn Great Danes with the Em genotype show a melanistic mask on the head and the face.
The Piebald color is another prominent trait in Danes. Piebald is a recessive trait that makes it difficult to eliminate from a breeding program. It is also associated with deafness in extreme forms. This trait is a difficult one to eradicate in the breeding program of a Dane breed.