GM2 gangliosidosis is an inherited Lysosomal Storage Disorder affecting Japanese chins. Affected dogs have insufficient activity of the Enzyme hexosaminidase A, which is responsible for breaking down specific carbohydrates in the cells. As a result, there is an accumulation of a glycoprotein, GM2 ganglioside in cells, especially in cells of the nervous system, including the brain. Affected dogs typically present with symptoms of neurologic disease around 15 to 18 months of age. Symptoms include loss of balance, altered mental state and vision loss. Once an affected dog begins to show signs of the disease, the disease progression is rapid and dogs usually die within several months of initial presentation.