Quantitation of the enzymically deficient cross reacting material in GM1 gangliosidoses

Normal quantities of GM1 beta-galactosidase cross reacting material (CRM) (0.31-0.47 microgram/mg protein) were detected by a sensitive radial immunodiffusion assay in skin fibroblasts from patients with GM1 gangliosidosis type 1 and adult variants, whereas elevated levels were found in GM1 gangliosidosis type 2 (0.41-0.72 microgram/mg protein). The specific activity of the immunologically CRM towards GM1 ganglioside of normal fibroblasts was about 500 times that of type 1, 100 times that of type 2, and 30 times that of the adult variants.