1. Type 1b and type 1c glycogen-storage disease are caused respectively by deficiencies of the glucose-6-phosphate translocase and the phosphate/pyrophosphate translocase of the human hepatic microsomal glucose-6-phosphatase system.
2. Current methods of unequivocally diagnosing type 1b and type 1c glycogen storage disease are indirect and complex.
3. We have therefore developed a simple, rapid and direct microfiltration assay for the glucose-6-phosphate translocase and the phosphate/pyrophosphate translocase.
4. We have demonstrated that the microfiltration assay can be used to directly diagnose type 1b and type 1c glycogen-storage disease in microsomes isolated from hepatic needle-biopsy samples.