GM2 Gangliosidosis (Japanese Chin Type)
Affected Genes: HEXA
Inheritance: Autosomal Recessive
Variant(canFam6):
chr30:35778293: C>T
Breed: Japanese Chin
General Information: GM2 Gangliosidosis (GM2) (Japanese Chin Type) is a genetic lysosomal storage disorder affecting dogs, particularly impacting the nervous system, including the brain. This condition results from insufficient activity of the enzyme hexosaminidase A, which is vital for breaking down certain carbohydrates within cells. The lack of this enzyme causes an accumulation of GM2 ganglioside, a glycoprotein, leading to cellular damage. Dogs with GM2 typically exhibit symptoms between 15 to 18 months of age, including loss of balance, altered mental state, and vision loss. Once symptoms appear, the disease progresses rapidly, often resulting in death within several months.
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 for GM2 Gangliosidosis (GM2) (Japanese Chin Type) involves screening for mutations in the HEXA gene to determine carrier status. This disease is inherited in an autosomal recessive pattern, meaning a dog must inherit two copies of the mutated gene, one from each parent, to develop the disease. Carriers do not typically show symptoms but can pass the mutation to their offspring. When two carriers are bred, each puppy has a 25% chance of being affected and a 50% chance of being a carrier. To prevent producing affected puppies and eliminate the mutation from breeding lines, it is crucial to avoid breeding two carriers. Dogs free from the mutation do not pose a risk of having affected puppies, making genetic testing an essential tool in responsible breeding practices.
References:
Sanders DN, Zeng R, Wenger DA, Johnson GS, Johnson GC, Decker JE, Katz ML, Platt SR, O’Brien DP. GM2 gangliosidosis associated with a HEXA missense mutation in Japanese Chin dogs: A potential model for Tay Sachs disease. Mol Genet Metab. 2013 108(1):70-75.