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Ganglioside storage diseases are defects of lysosomal hydrolase enzymes that result in accumulation of gangliosides (glycosphingolipids that are major constituents of plasma membranes in a variety of cells, especially neurons) and glycolipid substrates of these hydrolases within lysosomes of most neurons throughout the nervous system, including brain, spinal cord, and autonomic ganglia. The disease has been described in a variety of species, including cats, dogs, cattle, sheep, mice, and humans. In dogs, the accumulation of ganglioside in the brain is due to deficiency of acid beta-galactosidase. In most of the gangliosidoses, total ganglioside content of the brain is high in clinically affected animals. Asialo (sialic acid free) derivatives of the gangliosides also accumulate in the brain and liver. High levels of other neutral glycosphingolipids may also be found. In some instances, different substrates are stored in neural and visceral tissues, probably reflecting the heterocatalytic activity of the deficient enzyme. In affected Portuguese Water dogs, clinical signs of GM1 Gangliosidosis are typically observed at around 4 to 5 months of age. In most cases, the disease is clinically manifested as a neurodegenerative disorder. Common signs of disease include vision problems, lethargy, difficulty walking, and death in a period of approximately 8 months to 1 year of age.
DNA Test
A blood assay for the diagnosis of GM1 Gangliosidosis was developed in the late 1980 s and has been the most accurate method of detection of the disorder until recently. This test allowed the detection of dogs affected by GM1 Gangliosidosis but failed to detect carriers of this disease since they display no clinical symptoms. Recently, a PCR based assay for the detection of GM1 Gangliosidosis in Portuguese Water dogs became available. This test implements the most recent advancements in molecular diagnostics by selectively targeting the gene associated with GM1 Gangliosidosis. Using the PCR, this gene can be detected, amplified, and analyzed to determine whether a dog is affected (homozygous recessive) or a carrier of the disease. Since the gene for GM1 Gangliosidosis is directly targeted by this method, results are 100% accurate. Breeders and veterinarians can use this test to diagnose GM1 Gangliosidosis, as well as screen for carriers of the disease to help ensure a healthy breeding line. |
