The D locus is the primary locus associated with diluted pigment, which results in coats that would otherwise be black or brown instead showing up as gray, or blue in the case of black, and pale brown or Isabella / Lilac / Lavender in the case of brown. The melanophilin gene has recently been shown to be responsible, but not all of the dilute causing mutations have been identified yet.
A recessive mutation in the melanophilin gene was identified as the cause of colour dilution phenotypes in the dog. Two alleles (variants) are described: the dominant full colour (D) and the recessive dilute (d). Two copies of dilute are needed to lighten black pigment to blue / grey and brown (liver / chocolate / cocoa / red in border collie) pigment to lilac / isabella / lavender (in Pomeranian). A diagnostic DNA test identifies the specific variants of the MLPH gene.
Please note that in the Chow Chow, Thai Ridgeback and Sloughi breeds, there is another mutation that can cause coat colour dilution, it is the D2 Locus mutation and in those breeds both D1 Locus and D2 Locus mutations must be tested for complete analysis.
Please note that in the Chihuahua, Italian Greyhound, Mudi (Hungarian Mudi) and Hungarian Pumi breeds, there is another mutation that can cause coat colour dilution, it is the D3 Locus mutation and in those breeds both D 1Locus and D3 Locus mutations must be tested for complete analysis.
Please note that dilution (blue, lilac, isabella, etc) is just a colour and that it is not known to be associated with any health conditions
KC
Please note that this test is part of the KC DNA testing scheme in Labrador Retriever. If you would like Laboklin to send the result to the KC, please sign the declaration at the bottom of the form to give us a permission . Please note that the KC will oly publish clear results but would make a note of any result received.
Colour Dilution Alopecia (CDA)
There is no test for CDA and there is no evidence that CDA is caused by dilution
CDA is a genetic recessive inherited condition that causes patches of hair thinning or loss and may also include flaky and/or itchy skin. CDA occurs in dilute dogs (homozygous for the dilute gene d/d) in some breeds, however there is no direct link between CDA and the dilute gene, and there is no evidence that the dilute gene is responsible for CDA. It is though that there are other, not yet identified, genetic factors causing CDA in dilute dogs of some breeds. Any colour can carry CDA but symptoms are only expressed in blue and isabella dogs affected by CDA.
breeding
Since CDA is a recessive gene, it can, in theory, be bred out of most lines by breeding dilute dogs with healthy coats. Breeding healthy dilute dogs with healthy dilute dogs is one way to reduce the occurrence of CDA until testing becomes available.
Breeds known to be affected by CDA:
- Bernese Mountain Dog
- Boston Terrier
- Chihuahua
- Chow Chow
- Dachshund
- Doberman Pinscher
- Great Dane
- Irish Setter
- Italian Greyhound
- Mudi (Hungarian Mudi)
- Newfoundland
- Saluki
- Schipperke
- Shetland Sheepdog
- Standard Poodle
- Whippet
- Yorkshire Terrier
