Generalized gangliosidosis: beta-galactosidase deficiency.

A profound deficiency (10- to 30-fold) of beta-galactosidase activity was found in tissues (liver, spleen, kidney, and brain) from two patients with generalized gangliosidosis; this deficiency is demonstrated as a failure to cleave both p-nitrophenyl-beta-D-galactopyranoside and ganglioside GM(1) labeled with C(14) in the terminal galactose. We believe that this enzymic defect is responsible for the accumulation of ganglioside GM(1) and is the fundamental enzyme defect in generalized gangliosidosis.