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Dilute Coat Colour D-Locus and New D2-Locus

Description:

The MLPH gene codes for a protein called melanophilin, which is responsible for transporting and fixing melanin-containing cells. A mutation in this gene leads to improper distribution of these cells, causing a dilute coat colour. This mutation is recessive so two copies of the mutated gene (or "d" allele) are needed to produce the dilute coat colour.

This mutation affects both eumelanin and phaeomelanin pigments, so black, brown and yellow dogs are all affected by the dilution. However, this effect is more pronounced in black dogs. A dilute black (BB or Bb) dog is generally known as blue, though names do vary for different breeds, such as charcoal or grey. A diluted chocolate (bb) dog is often referred to as a lilac and a diluted yellow (ee) is known as a champagne.

Because the mutation responsible for the dilution phenotype is recessive, a dog can be a carrier of the dilution gene and still appear to have a normal coat colour. These dogs can pass on either the full-coloured or dilute allele to any offspring. This means that two dogs that appear full-coloured can have a dilute puppy. This makes DNA testing for the D-Locus an important breeding tool, whether breeding for a dilute coat, or to avoid it.

 

*Animal Genetics now offers a test for a second recessive mutation affecting dilution of coat color. This mutation was identified in a number of dog breeds where individual dogs had a diluted coat color, yet tested non-dilute. The additional variant works with the MLPH variant to dilute hair and skin in the same way. A diluted dog can be either d/d, d/d2 or d2/d2. When a dilute test is requested, Animal Genetics tests for both d and d2 alleles.

Chocolate Dilute Basic Colour Description
B/B or B/b D/D Black
B/B or B/b d/d or d2 Blue
b/b D/D Liver/Chocolate
b/b d/d or d2 Lilac
e/e D/D Yellow
e/e d/d or d2 Champagne

D Locus Testing:

Animal Genetics currently offers a test for the D-Locus to determine how many copies of the recessive allele a dog carries.

Dogs can be DNA tested at ANY age.

Sample Type:

Animal Genetics accepts buccal swab, blood, and dewclaw samples for testing. Sample collection kits are available and can be ordered at Canine Test Now.

Testing Is Relevant for the Following Breeds:

All breeds.

Results:

Animal Genetics offers DNA testing for 2 different types of dilute. The genetic test verifies the presence of the mutations and presents results as one of the following:

 

* Additional causes of this trait may exist. A negative result for this mutation does not eliminate the possibility that an additional, yet unidentified mutation or mutations in the genome may lead to a similar trait:

D/D Non-dilute The dog carries two copies of the non mutated MLPH allele. In most cases the dog will express a normal, non-dilute coat color and will always pass on a copy of the "D" allele to all offspring.
D/d Carrier of dilute Both the dominant and recessive MLPH alleles detected. In most cases the dog will have a normal, non-dilute coat and is a carrier of the dilute coat color. The dog can pass either MLPH allele on to any offspring.
d/d Dilute The dog has two copies of the recessive mutated MLPH allele. In most cases the dog will have a dilute colored coat. He will always pass on a copy of the MLPH allele on to any offspring.
D/d2 Carrier of dilute Both the dominant non mutated MLPH allele and recessive d2 mutated MLPH alleles detected. In most cases the dog will have a normal, non-dilute coat and is a carrier of the d2 dilute coat color. The dog can pass either MLPH allele on to any offspring.
d2/d2 Dilute The dog has two copies of the d2 recessive mutated MLPH allele. In most cases the dog will have a dilute colored coat and will always pass on a copy of the MLPH allele on to any offspring.
d/d2 Dilute The dog carries one copy of d and one copy of d2 mutated MLPH allele. In most cases the dog will have a dilute colored coat and will always pass on a copy of either MLPH mutated allele on to any offspring.