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Primary Open Angle Glaucoma (Discovered in Petit Basset Griffon Vendeen)

Primary Open Angle Glaucoma (POAG) is a disorder that results in an increase in eye pressure, leading to damage to the optic nerve and retina, and blindness if left untreated.

Key Signs

Elevated intraocular pressure, Loss of vision, Ocular pain

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

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

The loss of vision from glaucoma often occurs gradually over a long period of time and the first clinical signs frequently go unnoticed. Glaucoma is usually diagnosed when intraocular pressure has been elevated enough to cause loss of vision and pain. The clinical signs include pupil dilation, redness in the eye, corneal opacification, mild enlargement of the eye, possible partial lens luxation, and abnormalities in the optic nerve and retina. Glaucoma typically affects both eyes but not necessarily simultaneously. The age of onset is typically in middle-age. Glaucoma is diagnosed based on clinical signs, a thorough eye examination, measurement of intraocular pressure, and gonioscopy.

Intraocular pressure should be measured regularly (e.g. once every 3-4 months). If the pressure rises above normal, medications reducing intraocular pressure are required. If medications are unable to keep intraocular pressure within the normal range, surgical intervention may be considered. Emergency treatment is needed in the case of acute glaucoma which is very painful and rapid treatment may prevent loss of vision. In very advanced cases, where the eyes are very painful and vision is lost, enucleation is recommended.

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 mutation can be safely bred with a clear dog with no copies of the POAG mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the POAG 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 mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene ADAMTS17
Variant Insertion
Chromosome 3
Coordinate Start 40,812,274
Coordinate End 45,768,122

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Forman, O. P., Pettitt, L., Komáromy, A. M., Bedford, P., & Mellersh, C. (2015). A novel genome-wide association study approach using genotyping by exome sequencing leads to the identification of a primary open angle glaucoma associated inversion disrupting ADAMTS17. PLoS ONE, 10(12), 1–11. View the article