Partial deficiency of hexosaminidase component A in juvenile G M2 ‐gangliosidosis

SUMMARYA previously reported case of juvenile GM2-gangliosidosis was reinvestigated enzymatically with cellulose acetate electrophoresis. There was a partial deficiency of hexosaminidase component A, in contrast to the complete absence of this component in classical infantile GM2-gangliosidosis (Tay-Sachs disease) and to the complete loss of both components A and B in a case of total hexosaminidase deficiency. Juvenile GM2-gangliosidosis, therefore, may be tentatively characterized as partial hexosaminidase A deficiency, although this partial deficiency may be the result of complete deficiency of one or more specific subcomponents not yet identified within “component A” of hexosaminidase.