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GM1 Gangliosidosis (Discovered in the Portuguese Water Dog)

GM1 gangliosidosis is a disorder of progressive nervous system degeneration, resulting in vision impairment, head tremor, involuntary eye movements, limb weakness with difficulties in balancing and fatigue.

Key Signs

Neuromuscular dystrophy, Proportional dwarfism, Vision impairment, Head tremor, Involuntary eye movements, Limb weakness, Poor balance, fatigue, Poor appetite.

Age of Onset

0 to 2 yrs

Juvenile onset


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 GM1 Gangliosidosis

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 GM1 Gangliosidosis

Gangliosidosis is characterized by progressive neuromuscular dystrophy and proportional dwarfism. Clinical signs are typically first observable in two month olds and become obvious by 7 month. They include vision impairment, head tremor, involuntary eye movements, limb weakness with difficulties in walking/balancing and fatigue with loss of appetite.

Upon initial observation of clinical signs, affected dogs should be closely monitored to assess welfare, and devise a supportive care treatment plan. As clinically signs are progressive, affected dogs are usually euthanized on welfare grounds by 1 year of age.

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 GM1 Gangliosidosis mutation can be safely bred with a clear dog with no copies of the GM1 Gangliosidosis mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the GM1 Gangliosidosis 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 GM1 Gangliosidosis mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene GLB1
Variant G>A
Chromosome 23
Coordinate 3,754,313

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Wang, Z. H., Zeng, B., Shibuya, H., Johnson, G. S., Alroy, J., Pastores, G. M., … Kolodny, E. H. (2000). Isolation and characterization of the normal canine β-galactosidase gene and its mutation in a dog model of GM1-gangliosidosis. Journal of Inherited Metabolic Disease, 23(6), 593–606. View the article