The X-linked progressive retinal atrophy type 1 (XLPRA1) DNA test can be used by breeders and owners to screen their dogs to see if they carry the gene variant linked to this health condition.
Details about the disease
Progressive retinal atrophy (PRA) is a disease that causes problems with retina, which is a layer of tissue at the back of the eye. The retina contains special cells, called photoreceptors, that play a vital role in vision. In affected dogs, their photoreceptors begin to break down, causing vision problems that gradually become worse and can lead to total blindness.
Find out more about PRA.
Find out more about PRA.
Clinical signs
Affected dogs may begin to show signs of problems with their eyesight before they are two years old. At first, they may have problems seeing in dim light and, as the condition becomes worse, they may have trouble seeing in bright light and may become totally blind.
How is it inherited?
The disease is described as X-linked, which means that the faulty gene that causes this type of PRA is found on the X-chromosome. The X-chromosome helps to determine a dog’s sex.
Male dogs only have one X-chromosome, which they always inherit from their mother, while females have two X-chromosomes, which they inherit from both their mother and father.
In females, the disease acts in a recessive way, i.e., a female must inherit two copies of the faulty gene (one from her mother and one from her father) to be affected.
In males, because they only have a single copy of the X chromosome, the condition behaves as if it were dominant and male dogs are either healthy (they only have a healthy copy of the gene) or affected (they only have the faulty copy of a gene).
Male dogs only have one X-chromosome, which they always inherit from their mother, while females have two X-chromosomes, which they inherit from both their mother and father.
In females, the disease acts in a recessive way, i.e., a female must inherit two copies of the faulty gene (one from her mother and one from her father) to be affected.
In males, because they only have a single copy of the X chromosome, the condition behaves as if it were dominant and male dogs are either healthy (they only have a healthy copy of the gene) or affected (they only have the faulty copy of a gene).
Which laboratories do we record and publish the results from?
To find out which laboratories The Kennel Club is able to record results from, and which laboratories will send results directly to The Kennel Club, please refer to our website.
Please be aware, The Kennel Club has a set of criteria that we request DNA testing laboratories to meet to enable us to record their results, helping to maintain and protect the integrity of results that appear on a dog’s record. We strongly advise that customers ensure their chosen laboratory is included on our list if they wish The Kennel Club to record and publish the results. Results from laboratories not included on this list will not be recorded.
Breeding advice
The decision you make when choosing which dogs to mate must be informed and carefully planned.
If the health status of both sire and dam are known, the likely health status of any puppies produced can be predicted.
Please use the following table to note the outcome of mating a male and female with a known hereditary status:
If the health status of both sire and dam are known, the likely health status of any puppies produced can be predicted.
Please use the following table to note the outcome of mating a male and female with a known hereditary status:
| Clear male | Affected male | |
|---|---|---|
| Clear female | All puppies will be clear. | All male puppies will be clear. All female puppies will be carriers. |
| Carrier female | Each male puppy will have 50% chance of being affected. Each female puppy will have 50% chance of being a carrier |
Each male puppy will have a 50% chance of being affected. Each female puppy will have a 50% risk of being a carrier and a 50% risk of being affected. |
| Affected female | All male puppies will be affected. All female puppies will be carriers. |
All puppies will be affected. |
Breeding advice: If your dog is clear
Clear dogs should only be mated to other clear dogs. All other matings may produce affected puppies and should not be carried out.
Breeding advice: If your dog is a carrier or affected
Your dog should not be bred from. Mating this dog could produce affected puppies. Producing affected puppies that may develop XLPRA1 could have a serious impact on their health and welfare. A mating that may produce affected puppies should never knowingly be carried out. If this mating accidentally occurs, it is important to test all the puppies before they are bred from or are passed on to new homes. Veterinary advice should be sought as to the clinical management of any affected puppies.
Are clear dogs 100% clear?
Clear dogs are only known to be clear for the condition that they have been tested for, and may carry other unknown mutations which can be passed on to their offspring - it is almost certain that all individuals carry some versions of genes that if inherited in duplicate would result in disease. If a particular dog has many offspring that go on to breed themselves, these unknown mutations may then increase in frequency in the breed and a new inherited disease could emerge. In other words, no dog is completely risk free, but there are ways a breeder can reduce the risk of known and unknown inherited disease.
Making balanced breeding decisions
As well as considering the implications of a dog’s DNA test results, there are other equally important factors to consider when deciding whether two dogs should be mated together, such as temperament, genetic diversity, conformation, other available health test results, the general health of the dogs etc. Your breeding decisions should always be well balanced and take into consideration the qualities and compatibility of both the sire and dam that you are considering.
How to find out if a potential mate has been DNA tested
The health test results finder allows you to find the results of DNA tests carried out as part of our official DNA testing schemes for any dog on The Kennel Club’s Breed Register.