Dilute (D Locus)
Affected Genes: MLPH
Inheritance: Autosomal Recessive
Variant(canFam6):
D1=chr25:48618837 G>A,
D2=chr25:48647426 G>C
D3=chr25:48647388-48647389 1 bp insertion C
General Information: The D Locus (d), associated with the MLPH gene, affects coat color dilution in dogs through the distribution of melanin in the fur. Dogs with one copy of the dilute allele (D/d) may appear normal but can pass on the dilute trait, while those with two copies (d/d) exhibit noticeably lighter or washed-out colors compared to their standard coat color. This dilution is visible in what are typically black dogs appearing blue or grey and chocolate dogs appearing lilac or isabella. The phenotype extends to the dog's overall pigmentation, potentially affecting the color of the nose and eyes. Although primarily aesthetic, the trait can be linked with a condition known as color dilution alopecia, which can cause hair thinning or loss in some breeds.
Gene / Testing Information: Genetic testing for the D Locus (d) involves identifying mutations in the MLPH gene, which can predict whether a dog will display the dilute coat color trait and help breeders make informed decisions. This test identifies the d1, d2, and d3 alleles responsible for the dilution of the eumelanin and phaeomelanin pigments. The inheritance pattern of this trait is autosomal recessive, meaning that two copies of the dilute allele (d/d) are necessary for the diluted coat color to express. Carriers (D/d) do not exhibit a diluted coat but can produce diluted offspring if bred with another carrier. Breeding practices should involve testing potential breeding pairs to manage the propagation of this trait responsibly, especially since it can be associated with alopecia in some dogs. This careful genetic consideration ensures the health and well-being of the offspring, preventing the potential spread of associated health issues.
References:
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