DNA Dilute D-Locus/D2-Locus

Dilute Coat Colour D-Locus and New D2-Locus.

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.

Dogs can be tested at any age.

Possible Test Results :

• D/D - Non-Dilute
• D/d - Dilute Carrier
• d/d - Dilute
• D/D - Hereditary Non-Dilute
• D/d - Hereditary Dilute Carrier
• d/d - Hereditary Dilute