Glycogen Storage Disease Type Ia (Discovered in the Maltese)

Glycogen Storage Disease (GSD) Type Ia is a severe metabolic disorder causing critically low blood sugar levels.

Key Signs

Hepatomegaly, Hypoglycemia, Lactic acidosis, Hyperuricemia, Coma, Death

Age of Onset

At birth

Present at birth


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 GSD

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 GSD

GSD Ia is characterized by hypoglycemia (low blood sugar). Failure of glucose metabolism causes glycogen accumulation leading to hypoglycemia, lactic acidosis causing low blood pH, coma, and death. Affected puppies are weak and they rarely survive more than a few weeks.

Management of affected puppies consists of a high-starch diet fed frequently throughout the day to control hypoglycemia with only small amounts of protein and fat in the diet to provide required nutrients. Experimental gene therapy has successfully treated this disorder in dogs.

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

Technical Details

Gene G6PC
Variant G>C
Chromosome 9
Coordinate 20,138,777

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Kishnani, P. S., Bao, Y., Wu, J. Y., Brix, A. E., Lin, J. L., & Chen, Y. T. (1997). Isolation and nucleotide sequence of canine glucose-6-phosphatase mRNA: Identification of mutation in puppies with glycogen storage disease type Ia. Biochemical and Molecular Medicine, 61(2), 168–177. View the article