UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory

GM1 Gangliosidosis - Shiba Inu


GM1-gangliosidosis in Shiba Inu breed (SI-GM1) is a hereditary lysosomal storage disorder caused by abnormal accumulation of GM1 ganglioside, a fatty molecule (lipid) important for normal functioning of nerve cells in the brain. Affected dogs typically present with vision loss, head tremors, walking and balance issues, and weight loss by 6 months of age. The disease is progressive and lethal by 18 months.

SI-GM1 results from the loss of a nucleotide (c.1668delC) in the b-galactosidase gene, which codes for the beta-galactosidase enzyme. The deletion causes a change in the last 15% of the beta-galactosidase enzyme that renders it dysfunctional. In nerve cells, beta-galactosidase is found in the lysosomes, vesicles inside the cells that break down and recycle molecules. In dogs with defective beta-galactosidase, accumulation of GM1 gangliosides leads to progressive damage of nerve cells of the brain and central nervous tissue.

SI-GM1 is inherited in an autosomal recessive fashion, which means that males and females are equally affected and that two copies of the defective gene are needed to cause the disease.  Dogs with one normal and one affected gene (carriers) are normal and show no sign of the disease.

The VGL offers a genetic test for SI-GM1. This mutation has not been identified in other breeds with GM1-gangliosidosis and is different from the mutation identified in Portuguese Waterdogs. Genetic testing assists veterinarians with diagnosis of SI-GM1 and helps breeders to identify carriers to avoid breeding these together. Mating of carriers is expected to produce 25% of affected puppies.

Testing Recommended for: Shiba Inu

Allow 3-6 business days for results.

Results reported as:

N/N Normal - no copies of the SI-GM1 mutation
N/G Carrier - 1 copy of the SI-GM1 mutation; dog is normal
G/G Affected - 2 copies of the SI-GM1 mutation; dog will develop GM1 gangliosidosis

Yamato O, D. Endoh, A. Kobayashi, Y. Masuoka, M. Yonemura, A. Hatakeyama, H. Satoh, M. Tajima, M. Yamasaki and Y. Maede. (2002) A novel mutation in the gene for canine acid b-galactosidase that causes GM1-gangliosidosis in Shiba dogs. J. Inherit. Metab. Dis. 25:525-526.

Veterinary Genetics Laboratory, Tel 530-752-2211, Email VGL