beta-Galactosidase deficiency in an adult: a biochemical and somatic cell genetic study on a variant of GM1-gangliosidosis.

Biochemical data are presented of a 29-year-old male, who shows progressive psychomotor retardation and a beta-galactosidase deficiency in leucocytes and cultured skin fibroblasts. Somatic cell hybridization studies show that this variant of GM1-gangliosidosis is based on a different gene mutation than is present in types 1 and 2. No complementation is observed in fusion experiments with cells from type 3 variant.