S Locus (White Spotting, Parti, or Piebald)

General Information: The S Locus (S) (Dilute) involves mutations in the MLPH gene, which affects the distribution of melanin in a dog's fur, causing a dilution of the standard coat colors. Dogs with two copies of the mutated gene (d/d) exhibit noticeably lighter or 'diluted' coat colors, transforming black to blue or chocolate to lilac. This dilution also extends to the nose and footpads, changing their color as well. While aesthetically distinct, these diluted colors can be associated with health conditions such as color dilution alopecia, which can lead to hair loss and skin issues.

Gene / Testing Information: Genetic testing for the S Locus (S) (Dilute) involves identifying the presence of dilute alleles (d) in the MLPH gene. This gene controls the dilution of eumelanin (black and brown) and phaeomelanin (reds, yellows, and creams) pigments in the hair. The condition is autosomal recessive, meaning a dog must inherit two copies of the mutated gene to exhibit diluted coat colors. Carriers (D/d) do not display the dilute coat but can pass the allele to offspring. For breeding purposes, it's crucial to test potential breeding pairs to prevent the unintentional breeding of dogs with the d/d genotype, especially in breeds susceptible to color dilution alopecia. Dogs with a D/D genotype will not produce diluted offspring. This genetic testing is essential not only for achieving desired coat colors but also for avoiding the breeding of dogs that may develop associated health issues.