A case of type 2 GM1-gangliosidosis with long survival

An 11-year-old boy with type 2 G M1 -gangliosidosis was presented, providing further evidence for the clinical and biochemical heterogeneity of the disease. The patient had several characteristics of type 2 G M1 -gangliosidosis, but was different from so-called typical type 2 G M1 -gangliosidosis from the point of view of survival and the degree of G M1 -ganglioside accumulation. G M1 -gangliosidosis was diagnosed by absence of β-galactosidase activity in leukocytes and the parents had the enzyme levels of heterozygotes. However, the amount of the brain G M1 -ganglioside was accumulated to a less degree in comparison with that of typical type 2 G M1 -gangliosidosis, though the activity of G M1 -β-galactosidase in the brain was deficient to the same degree as in the typical case.