Glycogen Storage Disease Ia

Other Names: Von Gierke disease, GSD Ia, GSD1a
Affected Genes: G6PC
Inheritance: Autosomal Recessive
Mutation: chr9:20138777 (canFam3): G>C

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Common Symptoms

Glycogen storage disease Ia is an inherited metabolic disorder affecting dogs. Glycogen is the primary carbohydrate used by the body for energy. Affected dogs do not have sufficient enzymes to break down glycogen causing accumulation of glycogen in the organs of the dog, including the liver, heart and kidneys. Many affected dogs die In Utero or at birth resulting in small litter sizes with mummified fetuses and stillborn puppies. Symptoms in affected puppies that survive include failure to thrive, lethargy, low blood sugar, enlarged liver, coma and difficulty breathing. Without nutritional therapy affected dogs die within 2 months of age. Even with nutritional therapy affected dogs rarely survive to 6 months of age.

Breed-Specific Information for the Maltipoo

Maltipoo is included as a breed susceptible to glycogen storage disease Ia because of its close relatedness to the Maltese breed, which is known to develop this disease due to Mutation of the G6PC gene. The frequency of the causal mutation in the general maltipoo population is unknown.

Testing Tips

Genetic testing of the G6PC gene in maltipoos will reliably determine whether a dog is a genetic Carrier of glycogen storage disease Ia. Glycogen storage disease Ia is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the G6PC gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Maltipoos that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.

References

  • Brix AE, Howerth EW, McConkie-Rosell A, Peterson D, Egnor D, Wells MR, Chen YT. Glycogen storage disease type Ia in two littermate Maltese puppies. Vet Pathol. 1995 Sep;32(5):460-5. [PubMed: 8578635]
  • Kishnani PS, Bao Y, Wu JY, Brix AE, Lin JL, Chen YT. Isolation and nucleotide sequence of canine glucose-6-phosphatase mRNA - identification of mutation in puppies with glycogen storage disease type Ia. Biochemical & Molecular Medicine. 1997; 61: 168-177 [not in PubMed]
  • Kishnani PS, Faulkner E, VanCamp S, Jackson M, Brown T, Boney A, Koeberl D, Chen YT. Canine model and genomic structural organization of glycogen storage disease type Ia (GSD Ia). Vet Pathol. 2001 Jan; 38(1):83-91. [PubMed: 11199168]