GM1 - gangliosidosis 1

Gangliosidosis is a severe inherited disorder in which GM1 gangliosides accumulate in various tissues due to a deficiency of the enzyme beta-galactosidase. The disease is characterized by progressive neuromuscular dysfunction and growth impairment from an early age. Clinical signs begin to appear around 6 weeks of age and include proportional dwarfism, impaired coordination of movements, head tremors, strabismus, and nystagmus.

The disease is caused by a mutation in the gene for beta-galactosidase. It is a 19-bp duplication in exon 15 of the GLB1 gene (c.1688_1706dup) that disrupts mRNA splicing and leads to dysfunction of the resulting enzyme.

The mutation is inherited in an autosomal recessive manner. This means that the disease develops only in individuals who inherit the mutated allele from both parents. Carriers of the mutated gene are clinically healthy but pass the mutation on to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.

The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to avoid unintentional breeding of affected puppies.

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References:

Kreutzer, R., Leeb, T., Muller, G., Moritz, A., Baumgartner, W.: A duplication in the canine beta-galactosidase gene GLB1 causes exon skipping and GM1-gangliosidosis in Alaskan huskies. Genetics 170:1857-61, 2005. Pubmed reference: 15944348