Breeds Affected: Toy Poodle
Samples Accepted: Blood, Buccal Swabs
Disease Information: GM2 Gangliosidosis is also known as Sandhoff Disease or GM2 Gangliosidosis variant 0. Affected Toy Poodles first show symptoms of tremors, vision loss, vomiting and balance loss between 9-12 months of age. Neurological symptoms worsen quickly, leading to death at 18-23 months of age.
Inheritance Information: GM2G is autosomal recessive, meaning that animals with two copies of this allele will be affected. Animals with one copy of the gene will be clinically-normal carriers.
The possible genotypes are:
N/N The dog is normal, and cannot produce affected offspring.
N/gm2g The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/gm2g carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
gm2g/gm2g The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/gm2g carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/gm2g x N/N) without any risk of producing affected offspring. The offspring should be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/gm2g x N/gm2g ) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (gm2g/gm2g) should not be used for breeding.
Test Information: This mutation test identifies a single base pair deletion in exon 3 of the HEXB gene.
Rahman, M.M., Chang, H.S., Mizukami, K., Hossain, M.A., Yabuki, A., Tamura, S., Kitagawa, M., Mitani, S., Higo, T., Uddin, M.M., 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. Pubmed reference: 22766310. Doi: 10.1016/j.tvjl.2012.05.021.
Further information is available at the Online Mendelian Inheritance in Animals website.