Breeds Affected: Japanese Shorthair
Samples Accepted: Blood, Buccal Swabs
Disease Information: GM2-Gangliosidosis (variant 0), a lysosomal storage disorder, is also known as Sandhoff disease. It is a neuromuscular disease, and clinical signs can be seen in affected kittens between 6-8 weeks of age. They are generally smaller than littermates, and have tremors, a lack of coordination, and problems judging distance. These symptoms progress to the point where muscle control is so disrupted as to make walking and eating difficult, leading to euthanasia around 4 months of age.
Inheritance Information: GM2 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 cat is normal, and cannot produce affected offspring.
N/gm2 The cat is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/gm2 carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
gm2/gm2 The cat is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/gm2 carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/gm2 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/gm2 x N/gm2) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (gm2/gm2) should not be used for breeding.
Test Information:This mutation test identifies a single base pair change in the HEXB gene.
Kanae, Y., Endoh, D., Yamato, O., Hayashi, D., Matsunaga, S., Ogawa, H., Maede, Y., Hayashi, M.: Nonsense mutation of feline beta-hexosaminidase beta-subunit (HEXB) gene causing Sandhoff disease in a family of Japanese domestic cats. Res Vet Sci 82:54-60, 2007. Pubmed reference: 16872651. DOI: 10.1016/j.rvsc.2006.05.007.
Further information is available at the Online Mendelian Inheritance in Animals website.