Links to studies: Any and all black hair on the dog is included. recessive and relatively rare in the dog population as a whole, so isabella is generally a rarely seen colour. has a blue nose, it is genetically blue-pigmented. von Bomhard W, Mauldin EA, Schmutz SM, Leeb T, Casal ML. It is, however, the colour of the Weimaraner, and also occurs occasionally in a handful As with liver, the different d alleles all behave and interact in the same way, and don't appear to change the shade of the coat. There are just two alleles on this locus - D and d (although there are a number of slightly different d alleles that are phenotypically the same). Institute of Genetics. Genetic testing of the MLPH gene will reliably determine the number of copies of the color dilution gene variant that a dog carries. Weimaraner) or have very high incidence of dilute are far less likely to have CDA. It is likely that the dilution mutation occurred very early in the domestication of the dog, and has occured more than once. The gene causing dilution in dogs is known as MLPH (Melanophilin). Greying can also affect Eumelanin dilution is recessive, so D is non-dilute and d is dilute. "Coat color in the toller: Breed history and current genetics." A dog that is Dd or DD will have normal (non-dilute) pigment. The following dogs are not actually blues. 2002 Oct; 13(5):253-260. Paw Print Genetics®, Paw Print Pedigrees®, Paw Print Parentage™, Canine HealthCheck®, The Definitive Resource for Canine Genetic Health™, Great Dogs Start With Great Genetics™, Your Canine Genetic Resource™, Alopecia, Black hair follicular dysplasia, Blue Doberman syndrome, coat color dilution, Color dilution alopecia, Color mutant alopecia, D locus, D-allele, D-locus, Dilution gene, BHFD, CDA. However, when the dog is actually examined, it should be obvious that the nose is blue. 2006 Jun;17(3):182-8. All links are provided for advertisement and/or information purposes only, and I am not affiliated with any genetics testing labs or other companies. See the Health Problems page for more information on CDA. The dilution gene occurs on the D locus. The following dogs are not actually blues. No time to read the whole thing? All eumelanin is affected on a dd dog. Note the fairly pale red (phaeomelanin) areas on some of these dogs. Kim JH, Kang KI, Sohn HJ, Woo GH, Jean YH, Hwang EK. Further Info and Links If the dog has any black or liver then it is not a true dilute. Isabella (Dilute Liver) A potential candidate for non-MLPH dilution in dogs is TYRP2, which is known to cause some forms of dilution in mice, and the phenotype of these mice is certainly similar to the darker shades of blue in dogs. Most labs use numbering to label the D locus mutations - e.g. Eumelanin dilution is recessive, so D is non-dilute and d is dilute. Welle M, Philipp U, Rufenacht S, Roosje P, Scharfenstein M, Schutz E, Brenig B, Linek M, Mecklenburg L, Grest P, Drogemuller M, Haase B, Leeb T, Drogemuller C. MLPH genotype – Melanin phenotype correlation in dilute dogs. If the dilute gene is not present, the dog would be black. Black dogs become blue when they are dd on the D locus. Dilution may affect phaeomelanin slightly (although this is the source of some contention), but certainly not to the same extent as it affects eumelanin.