GM2 Gangliosidosis (Poodle Type)

Other Names: Sandhoff disease, Type 0 gangliosidosis
Affected Genes: HEXB
Inheritance: Autosomal Recessive
Mutation: chr2:57225684 (canFam3): 1 bp deletion (del G)

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Common Symptoms

GM2 gangliosidosis (poodle type) is an inherited Lysosomal Storage Disorder affecting toy poodles. 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, head tremors and vomiting. Once an affected dog begins to show signs of the disease, the disease progression is rapid and dogs usually die between the ages of 18 and 23 months.

Breed-Specific Information for the Toy Poodle

The Mutation of the HEXB gene associated with GM2 gangliosidosis (poodle type) has been identified in toy poodles. Though the exact frequency in the overall in toy poodle population is unknown, 0.2% out of 496 toy poodles from a randomly selected population from Japan were carriers of the mutation.

Testing Tips

Genetic testing of the HEXB gene in toy poodles will reliably determine whether a dog is a genetic Carrier of GM2 gangliosidosis (poodle type). GM2 gangliosidosis (poodle type) 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 HEXB 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. Toy poodles 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

  • Rahman MM, Chang HS, Mizukami K, Hossain MA, Yabuki A, Tamura S, Kitagawa M, Mitani S, Higo T, Uddin MM, Uchida K, Yamato O. A frameshift mutation in the canine HEXB gene in toy poodles with GM2 gangliosidosis variant 0 (Sandhoff disease). Vet J. 2012 Dec;194(3):412-6. [PubMed: 22766310]
  • Rahman MM, Yabuki A, Kohyama M, Mitani S, Mizukami K, Uddin MM, Chang HS, Kushida K, Kishimoto M, Yamabe R, Yamato O. Real-Time PCR Genotyping Assay for GM2 Gangliosidosis Variant 0 in Toy Poodles and the Mutant Allele Frequency in Japan. J Vet Med Sci. 2013 Oct 25. [PubMed: 24161966]
  • Tamura S, Tamura Y, Uchida K, Nibe K, Nakaichi M, Hossain MA, Chang HS, Rahman MM, Yabuki A, Yamato O. GM2 gangliosidosis variant 0 (Sandhoff-like disease) in a family of toy poodles. J Vet Intern Med. 2010 Sep-Oct; 24(5):1013-9. [PubMed: 20695991]