Type 3 (adult) GM1 gangliosidosis: case report.

GM1 gangliosidosis is usually a pediatric disease caused by hereditary acid beta-galactosidase deficiency. There have been a few cases in adults. We saw a 51-year-old Japanese man with type 3 GM1 gangliosidosis who was manifesting dementia, dysarthria, gait disturbance, and limb rigidity. Radiologic studies showed platyspondylia, acetabular hypoplasia, and flattened femoral heads. Biochemical analysis revealed generalized acid beta-galactosidase deficiency.