Common Symptoms
GM2 Gangliosidosis (Shibu Inu Type) is an inherited Lysosomal Storage Disorder affecting dogs. Affected dogs have insufficient activity of the Enzyme hexosaminidase B, which is responsible for breaking down specific carbohydrates in the cells. As a result, there is an accumulation of a glycoprotein, GM2 ganglioside, in cells, especially cells of the brain and nervous system. Affected dogs typically present with symptoms of neurologic disease around 9 to 12 months of age. Symptoms include vision loss, difficulties walking, loss of balance, and head tremors. The disease progression is rapid once a dog begins to show signs. Affected dogs die or are humanely euthanized shortly after diagnosis.
Testing Tips
Genetic testing of the HEXA gene will reliably determine whether a dog is a genetic Carrier of GM2 Gangliosidosis (Shibu Inu Type). This disease 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 HEXA 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. Dogs 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
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Wang P, Henthorn PS, Galban E, Lin G, Takedai T, Casal M. Canine GM2-Gangliosidosis Sandhoff Disease Associated with a 3-Base Pair Deletion in the HEXB Gene. J Vet Intern Med. 2018 Jan;32(1):340-347.
[PubMed: 29106755]
