The hnRNP associated with lethal yellow gene (RALY gene) defines whether tan points or saddle tan is expressed in Basset Hounds and Pembroke Welsh Corgi dogs. Black and tan colour is characterized by light colour on the muzzle, above the eyes (tan points) and on the undersides of the dog on otherwise dark coat. Saddle tan resembles black and tan colour but the lighter areas are expanded leaving usually only the back to have dark patch. Saddled tan dogs are usually born black-and-tan and the black recedes as the dog grows. The coat colour is further complicated by the interaction with the E-locus, K-locus, A-locus and a yet unidentified gene. In order for the saddle tan pattern or tan points to be expressed, the dog needs to have at least one copy of the E or Em allele at the E-locus, two copies of the ky allele at the K-locus and one or two copies of the at allele at the A-locus. The Coat Colour Saddle tan vs black-and-tan test (H353) tests for the genetic status of the RALY gene. The RALY gene has two variants (alleles). The allele WT is dominant and causes the saddle tan coat colour. Only when the dog has two copies of the recessive allele dup the coat colour is black-and-tan. The saddle tan coat colour is present in a limited number of dog breeds including some of the terriers, scent hounds and herding dogs. In breeds that have only tan point dogs and no saddled tan dogs, the tan pointed dogs can have any genotype for the RALY gene. This suggests that more complex interactions are behind tan points in breeds that are not able to express saddle tan.
The Coat Colour Saddle tan vs black-and-tan test encloses the following results:
|
RALY gene |
Coat Colour |
|---|---|
|
WT/WT |
Saddle tan, only allele WT will be passed on to an offspring |
|
WT/dup |
Saddle tan, either allele WT or dup will be passed on to an offspring |
|
dup/dup |
Black-and-tan, only allele dup will be passed on to an offspring |
