Tan Point Genetics and the Griffon
An AWPGA Board Report
So…how do you recognize a Griffon affected by the “Tan Point” gene? The accompanying photographs show Griffons who are affected. Essentially, the affected dog will normally have a tan spot above each eye, a tan muzzle, tan on the legs below the elbows, tan hair in the ears, and tan around the anus. Some more severely affected dogs can also have a tan blaze across the chest. As we know it now, this is strictly a cosmetic affliction leading to an atypical appearance. If your dog doesn’t display these attributes, it doesn’t rule its possibility out as a carrier of this gene.
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In basic terms, there are three DNA profiles your dog could have when tested for the K Locus. The first is an Clear dog (one that neither shows tan points nor is a carrier), reflected as KB/KB. The second is a Carrier dog, reflected as KB/ky. Finally, an affected and therefore Tan Point dog, reflected as ky/ky.
How do we get them? Here’s what various breedings would produce (all percentages represent puppies in the resulting litter).
Carrier to Carrier - approximately 25% will be Clear, 25% will be Tan Point and 50% will be Carriers.
Clear to Carrier - 50% will be Carriers and 50% will be Clear
Tan Point to Carrier - 50% will be Tan Point and 50% will be carriers
Tan Point to Clear - 100% will be Carriers
Tan Point to Tan Point - 100% will be Tan Point
These percentages are not firm and can vary from litter to litter.
Note: It takes just one puppy in a litter to indicate that both parents are carriers.
The $64,000 question remains, “Where did this come from?” This we don’t know for sure and can only speculate. However, it’s our understanding the French have been seeing Griffons with atypical coloration since the 1970’s.
We do know of a handful of dogs that are known carriers based on their production of these puppies. Based on this handful of dogs and their past breeding, there are a few thousand carriers and many who are producing carriers today. Accurate testing can be accomplished by one lab; Veterinary Genetic Services (www.vetgen.com). This test costs $55. We have validated the tests provided by VetGen by testing dogs either known or expected to have specific results and these results returned as expected.
This concerns the AWPGA Board to a level to have appointed a special Health and Genetics sub-committee to look into this and provide recommendations to the Board on how to reduce the spread or eliminate this from our gene pool to the fullest extent possible. They will also suggest protocols for guaranteeing the integrity of the testing process. This subcommittee is chaired by the Health and Genetics Chair, Katherine March and is made up of the following members: Lisa Boyer D.V.M., Phil Wolthuis, and Philippe Roca.
If you have produced any Tan Point dogs, please let the Health and Genetics committee know about the breeding that produced it. Also, if you have any additional input or suggestions, provide them to the committee or a Board Member.
Bottom line…we want to remove the Tan Point gene from the Wirehaired Pointing Griffon gene pool. Please read the following article written by Dr. Sheila Schmutz on the genetic make-up of this gene and view the photographs to help you to further identify this gene in your Griffon.
Additional information can be obtained by following this link... www.vetgen.com/canine-strategies.html
Wirehaired Pointing Griffon Coat Color Genetics
By Sheila Schmutz, Ph.D.
Department of Animal and Poultry Science,
University of Saskatchewan
In the past year or two I have received several emails from owners of versatile hunting dogs about dogs or pups that don’t have quite the coloration that the owners or breeders expected for that breed. I receive these because I have a website, http://homepage.usask.ca/~schmutz/dogcolors.html , on this subject. This website is based on the DNA research we’ve done in my lab or that has been done in the labs of my collaborators or colleagues.
Our first DNA study was on brown in dogs. We proved that brown was caused by a dog having two mutant copies of the TYRP1 gene. There are actually three different mutations that can cause brown. The dog need not have two of the same mutations to be brown, but it must have two. If it has only one mutant copy of the gene TYRP1, it will be black. At least two of the mutations have been found in Griffons. It is possible the third, more rare one, is also there and that we have just not tested enough Griffons to detect that one yet.
I was recently surprised to discover that the AKC and the FCI and the Quebecois standard all say that the Griffon can be brown or orange. Brown is a eumelanin pigment in the black family and orange is a phaeomelanin pigment in the red family.
Does this also mean that brown Griffons can have tan markings on them as in the tan of Gordon Setters? That tan is also a phaelomelain color in the red family. I was not expecting that either orange or therefore tan would be considered an expected color in this breed.
When I look at photos of Griffons on various websites, I note that some do have mostly brown fur (with white hairs intermingled usually, known as roan to geneticists) but some have tan eyebrows and muzzle. Often one can’t see the feet because they are in the grass or cut off of the photo. Such dogs would be called brown-and-tan in most breeds or tricolor in others since they have brown, tan and white.
The “and-tan” markings are sometimes called tan points. Although dogs must have two mutant alleles at the ASIP gene to have tan points (i.e. at/at genotype), this is not sufficient. They must also be ky/ky at the DEFB103 gene. Most European hunting breeds are KB/KB at this gene instead and do not show any pheaomelanin coloration at all. So we don’t expect a tricolor German Wirehair or a tricolor German Shorthaired Pointer, but we do expect a tricolor English Pointer or a tricolor English Setter. All four of those breeds are usually at/at at the ASIP gene or A locus. The difference between the German breeds and the English ones is that the German ones are expected to always be KB/KB.
If a pup turns up with tan points or “and-tan” markings in a litter then it automatically means that each parent must have at least one ky and one at. Intuitively if one wanted to breed out the “and-tan” one might at first assume that one would order a DNA test for at, but actually it is best to order a test for KB instead. If the dog’s test results say it is KB/ky instead of KB/KB, then the owner knows that this dog could have pups that show tan points.
There are a couple choices then. One could decide not to breed such a dog at all or one could decide that other great hunting traits warrant that it still be bred and that a pup that does not carry the ky be chosen from among its offspring to carry on the line. If a KB/ky heterozygote is bred, then ideally its mate would be DNA tested as KB/KB. In such a mating no pups will be born that have the undesired tan point pattern, but half of the pups would be carriers of ky. Essentially the choice is whether one wants to eliminate the allele immediately or just the pattern immediately.
DNA testing can be done by collecting a cheek brush sample and mailing it in to a company that offers testing for KB, with the appropriate payment. Cheek brushes travel easily through the mail and so the company need not even be in the same country as the dog.
The DNA test for the KB allele was published in SCIENCE in October 2007. Therefore the test has not been available for very long yet and many dog owners are not aware that this test could be used to help them select dogs that are brown from those that are brown-and-tan.
(August 5, 2009)
Published in the Griffonnier Volume 21, Number 2, June 2010