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Mammals have two pigments that are the basis of hair color: eumelanin (black) and pheomelanin (red or yellow). The gene involved in the production of these pigments in many species including dogs is Melanocortin 1 Receptor (MC1R) which is also called Extension. Other genes modify these pigments to produce the variety of colors and patterns found in the domestic dog. The Brown gene, Tyrosinase-Related Protein 1 (TYRP1), is a modifier that dilutes black pigment to brown but does not affect red pigment. Other genes involved in dog coat color include Agouti (ASIP) which organizes the distribution of black and red pigments, Beta-defensin (CBD-103) which is unique to dogs and responsible for dominant black, and Dilute (MLPH) which dilutes black and red pigments. Other genes that add white patterns and dilute colors are also present in dogs but are specific to certain breeds. Below are expanded descriptions of the genetic tests offered by the Veterinary Genetics Laboratory for dog coat color.
ORDER TEST KITS - Allow 5-10 business days for test results.
Detailed Coat Color Information
MC1R GeneMC1R Gene. The three common alleles (variants) of this gene are melanistic mask (Em), black (E) and red (e). A forth allele, EG, is unique to Afghan and Saluki breeds. Em and E are dominant to e, therefore a dog must have 2 copies of e to be clear red/yellow. Some breeds are fixed for either black or red pigment, such as the Large Munsterlander for black and Irish Setters and Golden Retrievers for red.
Melanistic face mask is found in a variety of breeds including but not limited to Afghans, Akitas, Boxers, French Bulldogs, German Shepherds, Great Danes, Greyhounds, Pug Dogs and Whippets. For Pug Dogs and Boxers the trait is fixed, while it is variable in other breeds. Dogs that are overall eumelanistic (black, blue or brown) may have the mask but it is indistinguishable from the body color. Dogs with white muzzles may have the mask gene but expression is overridden by white spotting patterns. The mask phenotype is caused by the Em variant (allele) at the MC1R gene. Em is dominant to the black E and red e alleles.
The VGL offers tests for Black/Red and Melanistic Mask. These two tests can be requested together or individually, as appropriate to the breed of dog.
The Black/Red DNA test is specific for the E and e variants. It is useful for those breeds that have both black- and red-colored dogs such as Dobermans and Labrador Retrievers.
References:
Schmutz SM, TG Berryere and AD Goldfinch. TYRP1 and MC1r genotypes and their effects on coat color in dogs. Mammalian Genome 13:380-387 (2002)
Schmutz SM, TG Berryere, NM Ellinwood, JA Kerns and GS Barsh. MC1R studies in dogs with melanistic mask or brindle patterns. Journal of Heredity 94:69-73 (2003)
Newton JM, AL Wilkie, L He et al. Melanocortin 1 receptor variation in the domestic dog. Mammalian Genome 11:24-30 (2000)
1. If only Black/Red tests are requested, results are reported as:
E/E: 2 copies of black cannot have clear red/yellow offspring.
E/e: 1 copy of black, carrier of clear red/yellow. Can produce clear red/yellow puppies, depending on the genetics of the mate.
e/e: clear red/yellow.
2. If only the mask test is requested, results are reported as:
Em/Em: 2 copies of mask are present- dog has mask
Em/N: 1 copy of mask is present- dog has mask
N/N: no copies of mask are present
3. If both black/red and mask tests are requested, results are reported as:
Em/Em: 2 copies of mask are present- dog has mask
Em/E: 1 copy of mask is present- dog has mask and black
Em/e: 1 copy of mask is present- dog has mask and carries clear red/yellow
E/E: 2 copies of black, dog cannot have clear red/yellow offspring
E/e: 1 copy of black, carrier of clear red/yellow
e/e: clear red/yellow
Agouti
The Agouti Signaling Protein (ASIP) gene interacts with the MC1r gene to control red and black pigment switching in most mammals including dogs. Dog coat color is further complicated by the interaction of other genes that restrict agouti expression such as the dominant black gene – Beta-Defensin 103. There are 4 known alleles (variants) of agouti listed here with corresponding color pattern in order of dominance: fawn/ sable (ay) yellow to red with some dorsal black tipped hairs, wild sable (aw) banded hairs of yellow and black as in seen in wolves and coyotes, black-and-tan (at) black dorsal hairs with tan hair on cheeks, eyebrows and undersides, and recessive black (a) all black as seen in some herding dogs. The Eurasier dog breed has all 4 alleles while some breeds are fixed for only one variant such as the Norwegian Elkhound for wild sable and the Beagle for black-and-tan. For many breeds, there are 2 or 3 alleles possible and it may be advantageous for breeders to predict the possible colors of offspring resulting from specific matings. The agouti test is also useful to help determine the color of dogs that have white patterns that may obscure the distribution of the colored pigment.
The Veterinary Genetics Lab offers a test for agouti to assist breeders/owners to determine the agouti alleles present in their dogs. This test will help determine possible coat color outcomes from specific matings. Results are reported as:
ay / ay Homozygous for fawn/ sable.
ay / aw Dog is fawn and carries wild sable.
ay / at Dog is fawn and carries black-and-tan.
ay / a Dog is fawn and carries recessive black.
aw/ aw Homozygous for wild-sable.
aw/ at Dog is wild-sable and carries black-and-tan.
aw/ a Dog is wild-sable and carries recessive black.
at/ at Homozygous for black-and-tan.
at/ a Dog is black-and-tan and carries recessive black.
a/a Homozygous for recessive black.
References:
Berryere TG, JA Kerns, GS Barsh and SM Schmutz. Association of an Agouti allele with fawn or sable coat color in domestic dogs. Mammalian Genome 16: 262-272 (2005)
Kerns JA, J Newton, TG Berryere, EM Rubin, JF Cheng, SM Schmutz and GS Barsch. Characterization of the dog Agouti gene and a nonagouti mutation in German Shepard Dogs. Mammalian Genome 15:798-808 (2004).
Dreger DL and SM Schmutz. A SINE insertion causes the black-and-tan and saddle tan phenotypes in domestic dogs. Journal of Heredity 102(S1):S11-S18 (2011).
Brown*
TYRP1 Gene. There are two alleles: the dominant full color (B) and the recessive brown (b). Two copies of brown are needed to dilute black pigment to brown. For red or yellow dogs, the brown allele does not dilute the hair color, but will change the color of nose and foot pads from black to brown if two brown alleles are present.
Brown results are reported as:
B/B: Does not carry brown - cannot have brown offspring
B/b: 1 copy of brown present - carrier
b/b: 2 copies of brown present - black pigment (if present) is diluted to brown, red/yellow dogs have brown noses and foot pads
*Note regarding French Bulldogs: The dark chocolate color (dark brown hair with black nose) will not be detected by the brown gene test. The genetic basis for this color is not known at this time.
References:
Schmutz SM, TG Berryere and AD Goldfinch. TYRP1 and MC1r genotypes and their effects on coat color in dogs. Mammalian Genome 13:380-387 (2002)
Schmutz SM, TG Berryere, NM Ellinwood, JA Kerns and GS Barsh. MC1R studies in dogs with melanistic mask or brindle patterns. Journal of Heredity 94:69-73 (2003)
Newton JM, AL Wilkie, L He et al. Melanocortin 1 receptor variation in the domestic dog. Mammalian Genome 11:24-30 (2000)
Dilute (Blue)
A recessive mutation in the melanophilin (MLPH) gene was identified as the cause of color dilution phenotypes in the dog. Two alleles (variants) are described: the dominant full color (D) and the recessive dilute (d). Two copies of dilute are needed to lighten black pigment to grey (often called blue) and red pigment to cream (also called buff). A diagnostic DNA test identifies the specific variants of the MLPH gene.
Results from the DILUTE test are reported as:
D/D Full color, no dilute gene present
D/d Full color, carries 1 copy of the dilute gene
d/d Dilute, 2 copies of the dilute gene
Reference:
Drögemüller C, U. Philipp, B. Haase, A-R Günzel-Apel & T Leeb. A noncoding melanophilin gene (MLPH) SNP at the splice donor of exon 1 represents a candidate causal mutation for coat color dilution in dogs. Journal of Heredity 98(5):468-473 (2007).
Dominant Black
The wide variety of coat colors in mammals is achieved by the production of two pigments, eumelanin (black) and pheomelanin (red or yellow). In most mammals, the switching between these 2 pigments is controlled by MC1R and Agouti genes. In dogs, original coat color research of pedigrees suggested that a third gene, named Dominant Black (K), was involved. This gene produces dominant black vs. brindle vs. fawn colors in breeds such as Great Danes, Pugs and Greyhounds among others. Researchers recently have discovered that dominant black is due to a mutation in a Beta-defensin gene (CBD103).
The Veterinary Genetics Laboratory offers a test that can assist owners of black dogs to determine if their dogs are homozygous for dominant black or if they carry brindle or fawn.
Results are reported as:
K/K 2 copies of dominant black are present, no brindle or fawn offspring will be produced
K/N 1 copy of dominant black is present, brindle or fawn offspring can be produced, depending on the genotype of the mate.
N/N Dog does not have the dominant black mutation.
Reference:
Candille Sophie I, C B Kaelin et al. A beta-defensin mutation causes black coat color in domestic dogs. Science 318, 1418 (2007) DOI: 10.1126/science.1147880