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Glycogen Storage Disease IIIa

Glycogen Storage Disease IIIa is an inherited metabolic disorder affecting breeds like Curly-Coated Retrievers, caused by insufficient enzymes to break down glycogen, leading to its accumulation in the liver and muscles and resulting in symptoms such as exercise intolerance, lethargy, and liver enlargement, typically presenting between one and two years of age.

Affected Genes: AGL

Inheritance: Autosomal Recessive

Variant(canFam6):
chr6:52728942: 1 bp deletion A

Breed: Curly Coated Retriever

General Information: Glycogen Storage Disease IIIa is an inherited metabolic disorder in dogs, where insufficient enzymes cause glycogen to accumulate in the liver and muscles. While symptoms are mild in the first year, affected dogs typically show signs such as exercise intolerance, lethargy, vomiting, and liver enlargement between one and two years of age. In some cases, dogs may collapse during exercise due to low blood sugar. The disease leads to progressive liver and muscle damage as glycogen continues to build up in cells.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Unlikely Affected

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing of the AGL gene can identify carriers of Glycogen Storage Disease IIIa, which is inherited in an autosomal recessive manner, requiring two mutated gene copies for the disease to develop. Carrier dogs typically show no symptoms but can produce affected pups if bred with another carrier, with each pup having a 25% chance of developing the disease and a 50% chance of being a carrier. Reliable genetic testing is crucial for informed breeding practices, and to avoid producing affected pups, carriers should not be bred together. Dogs without the mutation do not have an increased risk of having affected offspring.

References:
Gregory BL, Shelton D, Bali DS, Chen YT, Fyfe JC. Glycogen storage disease type IIIa in curly-coated retrievers. J Vet Intern Med. 2007 21(1):40-46.

Yi H, Thurberg BL, Curtis S, Austin S, Fyfe J, Koeberl DD, Kishnani PS, Sun B. Characterization of a canine model of glycogen storage disease type IIIa. Dis Model Mech. 2012 5(6):804-811.