Juvenile GM2 gangliosidosis. Biochemical and ultrastructural studies on a new variant of Tay-Sachs disease.

Abstract

Morphological and chemical studies were performed on a cerebral biopsy in a patient with the clinical course of late infantile amaurotic idiocy. Accumulation of the Tay-Sachs ganglioside, G M2 (G 5 ) was noted in both gray and white matter. Hexosaminidase A in serum and skin fibroblast cultures was reduced to 6.6% and 12% of total hexosaminidase activity, as contrasted with 57.3% and 49.0% in controls. On electron microscopic examination there was an accumulation of intraneuronal membranous cytoplasmic bodies, zebra bodies, other varieties of lipid bodies (including aggregates of the preceding types), and lipofuscin bodies. These findings indicate that the patient had juvenile G M2 gangliosidosis, a newly recognized G M2 ganglioside storage disease in which hexosaminidase A is partially active but apparently to an insufficient degree to prevent the slow evolution of neurological symptoms.