Health & Genetic issues


Hairlessness in Deerhounds

 

To maximise the Health and Welfare of Deerhounds, the Deerhound Club encourages Breeders to ensure that their breeding programmes strive to eliminate hereditary disorders and minimise genetic defects whilst continuing to ensure a wide genetic base for the breed

Hairless Deerhounds are occasionally born and recently two such puppies were born in a litter of five otherwise normal puppies. Puppies were born with a sparse coat that falls out by about 12 weeks of age.

These puppies prompted an investigation by two Finnish scientists, Drs Hytonen and Loki of the University of Helsinki, to identify the gene(s) responsible. They discovered a new mutation of a gene was responsible and that this was different from the already known genetic mutation responsible for hairlessness in Chinese Crested and Mexican and Peruvian Hairless dogs.

A more detailed summary of this study by Drs Hytonen and Loki is given by Sue Finnett below.
 
The DNA test for hairlessness in Deerhounds is now available and European clients are referred to the MyDogDNA product which is available to order from: www.mydogdna.com .

Here is a link to the full test content for Deerhounds: https://www.mydogdna.com/crm/index.html#en/breeds/519248a83cd390a0520001a7/deerhound/disorders . You will find the hairlessness test listed under Traits/Coat type.

We are currently referring members to the MyDogDNA product because we have been assured that this DNA test for Hairlessness has been validated using genotype control samples directly provided by the Lohi group.

 

Hairlessness In The Deerhound - A New Genetic Discovery Two genes have so far been identified to be associated with hairlessness in dogs. A recessive variant of the “FOX13” gene is responsible for sparse coats seen in the Chinese Crested as well as Mexican & Peruvian Hairless Breeds. In these breeds, the hairless variety generally retains coat or furnishings on some parts of the body. A recessive variant of the “SGK3” gene, identified in the Rat Terrier in the USA was harnessed in the development of the American Hairless Terrier. These are born with very sparse coats, all of which is shed within the first few weeks of life.

Hairless Deerhounds are occasionally born and there is generally more than one in the same litter. Two such puppies were recently born in a litter of five otherwise apparently normal Deerhounds. Their sparse hair coats were all gone by 3 months of age. A study of these two by Drs Hytonen & Loki of University of Helsinki, Finland, worked on the hypothesis that the hairlessness was genetically determined by an abnormal gene acting as a simple autosomal recessive. These investigators read the full genome of one of the hairless puppies and of a number of normal coated Deerhounds. They then looked for gene locations where both copies were the same (homozygous) in the hairless puppy, but where at the same location on the chromasome of the normal coated dogs, none of them carried two copies of that same version on the gene. Only two such locations were identified.

The SGK3 gene in both of the hairless Deerhounds had two defective copies (homozygous affected). This defect, named SGK3:c137_138insT, appears to be a previously unrecorded mutation. It occurred in the same gene as that of the American Hairless Terrier but is not the same mutation of the gene.

Of 64 Deerhounds with normal coats, 12% were found to carry a single copy of the SGK3:c137_138insT mutation (heterozygous carriers). None of the remaining Deerhounds studied carried the mutation (homozygous normal). Of ninety one Irish Wolfhounds studied none carried the defective gene.

The investigation has identified the genetic cause of the hairlessness in these Deerhounds as SGK3:c137_138insT. Any genetic test for the defective “hairless” Deerhound gene should need to be specific for SGK3:c137_138ins, not just to simply detect any change or other mutation of the SGK3 gene.

In conclusion it appears that hairlessness in these two Deerhounds was caused by a single autosomal recessive gene. The study suggests that about 1 in 8 Deerhounds might be carriers. If this is so then we could expect hairless puppies in about one of every 70 litters born. This would be to assume that this hairless version of the SGK3 gene occurs at the same frequency in the wider Deerhound population as in those studied and that it is randomly distributed amongst those hounds that are bred from.

As a note of caution, whilst it appears reasonable to assume that other cases of hairlessness in the Deerhound have been caused by this particular mutation, it is just possible that other mutations of the same or other genes have been involved. However for now it seems reasonable to assume that this genetic cause has solved the mystery of the hairless Deerhounds.

Commercial tests offered currently for hairlessness detect a “hairless” variant of the FOX13 gene. They do not detect the genetic defect, in the SGK3 gene, demonstrated to cause hairlessness in the Deerhound. It is believed that a commercial genetic test for the carrier state of hairlessness in Deerhounds is under development and may be available later this year. Until this is available it is important that Deerhound breeders do not rely upon commercially available genetic tests for hairlessness that detect mutations in the "wrong" gene or the "wrong" mutation in the right gene.

Sue Finnett BVM&S MRCVS 5th May 2019

Reference Hytönen, M.K. & Loki, H. Hum Genet (2019). https://doi.org/10.1007/s00439-019-02005-9. A frameshift insertion in SGK3 leads to recessive hairlessness in Scottish Deerhounds: a candidate gene for human alopecia conditions.

 

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