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Primary Open Angle Glaucoma and Lens Luxation (Discovered in Chinese Shar-Pei)

Primary Open Angle Glaucoma (POAG) is a disease where the pressure in the eye increases, causing pain and leading to blindness if untreated. The same mutation can also cause lens luxation (LL), or displacement of the lens in the eye.

Found in

1 in 1,000 dogs

in our testing

Key Signs

Eye redness, Eye pain, Increased intraocular pressure, Lens subluxation, Lens luxation, Blindness

Age of Onset

1 to 4 yrs

Junior to adult onset

Inheritance

Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with POAG and LL

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about POAG and LL

The first clinical signs are usually observed at the age of 3 to 6 years. The elevated eye pressure causes significant pain to the affected dog. Typical signs are red, itchy, squinting, watery, and cloudy eyes. In advanced cases, the globes are enlarged and blind. This mutation also causes lens luxation, likely secondary to the elevated intraocular pressure. Subluxation, or partial lens detachment, commonly occurs before complete luxation. When the lens luxates, it may do so either anteriorly or posteriorly. An anterior lens luxation is particularly serious and manifests as squinting, redness, and watering of the eyes and requires immediate veterinary care. Displacement of the lens in the other eye usually occurs weeks or months after the first luxation.

Routine eye examinations, for example once in every 3-4 months, are advisable. If pressure within the eye is elevated, ocular drops intended to lower the pressures are likely to be prescribed. Acute glaucoma is very painful and requires emergency treatment to prevent impairment of vision. Surgical intervention is needed in cases where local treatment isn’t sufficient for maintaining normal eye pressure. In chronic glaucoma cases where blindness and pain is present, surgical removal of the affected eye may be deemed the best therapy. Regular eye examinations also help in diagnosing lens luxation at its early stage. Treatment can be used to prevent the lens from luxating into the front chamber. Lens luxation can be treated surgically but has a better outcome if the lens is only partially detached. Primary anterior lens luxation is a condition that needs emergency treatment. Emergency treatment consists of drugs reducing intraocular pressure. The actual treatment consists of surgical removal of the lens. Treatment should be started as soon as possible to prevent blindness.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to develop. A carrier dog with one copy of the POAG and LL mutation can be safely bred with a clear dog with no copies of the POAG and LL mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the POAG and LL mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the POAG and LL mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene ADAMTS17
Variant Deletion
Chromosome 3
Coordinate Start 40,935,388
Coordinate End 40,935,393

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Farias, F. H. G. (2011). Molecular genetic studies of canine inherited diseases. View the article