Color dilution

Color dilution is a hereditary trait related to the presence of variants in the MLPH gene, resulting in lightening or dilution of the canine coat coloration.

Definition

The dilution trait is a specific pigmentation phenotype characterized by a more diluted and lightened coat color. Eye color and skin color may also be affected, thus manifesting a lighter coloration. The mutation occurs in the MLPH (melanophilin) gene involved in the transport of melanosomes in the melanocyte. The existence of this variant causes the modification of the coat coloration from black or brown to blue, gray or light brown tones; and from red to cream.

Genetic basis

The variant tested is also known as the "d1" allele. It is necessary for the dog to inherit two copies of the variant to obtain a more dilute coat coloration. The presence of a single copy would not result in the expression of the mentioned phenotype, but it can be transmitted to the dog`s offspring. However, it should be noted that it has been shown that a single copy of this variant in combination with a copy of another variant described as c.705G>C (not analyzed in our test) gives rise to a phenotype very similar to that obtained in d1/d1 homozygosis.

Other relevant information

Dogs with two copies of the variant are at increased risk of color dilution alopecia (CDA). This disease causes chronic inflammation of the skin and hair loss. Breeds commonly exhibiting the trait are American Staffordshire Terrier, Beagle, Doberman Pinscher, German Pinscher, Great Munsterlander, Miniature Pinscher and Rhodesian Crested.

Bibliography

Drögemüller C, Philipp U, Haase B, et al. A noncoding melanophilin gene (MLPH) SNP at the splice donor of exon 1 represents a candidate causal mutation for coat color dilution in dogs. J Hered. 2007;98(5):468-73.