GM1 Gangliosidosis in Cats
Bioguard Corporation GM1 gangliosidosis is a lysosomal storage disorder caused by deficiency of the enzyme β-galactosidase. Mutations in the GLB1 gene, encoding β-galactosidase, cause the progressive, neurosomatic, lysosomal storage disorder. Cats affected with gangliosidosis have progressive neurologic dysfunction around 3 months of age and premature death around one year old. Pathogenesis Gangliosides, normally hydrolyzed by β-galactosidase, are the main glycolipids of neuronal plasma membranes. Absent or reduced β-galactosidase activity leads to the accumulation of β-linked galactose-containing glycoconjugates including the glycosphingolipid (GSL) GM1-ganglioside in neuronal tissue. Instead of being broken down and recycled, this excess material is stored in membrane bound sacs (vacuoles) in cells. As the number of vacuoles increase, there are less available space and resources for normal cell function so that neuronal cell death and degeneration occurs, damaging the central nervous system and other organs. Clinical signs Kittens with GM1 gangliosidosis appear normal at birth and successfully achieve all developmental milestones. However, the accumulation of gangliosides in neuronal cells causes central nervous system damage. Clinical signs are apparent in cats at 2-3 months of age. Gangliosidosis is clinically characterized by discrete head and limb tremors and lack of coordination of movement. Other clinical signs include ataxia; tremor; visual disorder, which may have been due to cortical blindness; and seizures. The progressive accumulation of GM1 ganglioside in the central nervous system and cerebrospinal fluid ultimately proves fatal for cats at a young age. Diagnosis To rule other diseases causing symptoms similar to GM1 in cats, the diagnosis of gangliosidosis is carried out based on comprehensive findings using various types of specimens for histological, ultrastructural, biochemical and genetic analyses. A diagnosis of GM1 gangliosidosis requires biochemical identification of the storage product and enzyme deficiency. Affected animals had lower β-galactosidase activity in the liver and increased levels of GM1 gangliosides in the brain. In addition, DNA testing can be used to detect the mutation causing GM1 gangliosidosis in Korat cats; it can identify affected cats, carriers and normal cats, without the genetic mutation. Breeds such as the Siamese, Korat, Oriental Shorthair, Balinese, Havana Brown, Birman, Burmese, and Singapore Cat are more suscep-tible. It is recommended to conduct this test before breeding.
