A new variant of glycogen storage disease type 1: probably due to a defect in the glucose-6-phosphate transport system.

A new variant of glycogen storage disease (GSD) Type 1, with clinical symptoms and laboratory findings consistent with those of glucose-6-phosphatase (G6Pase) deficiency, is described. Assay of G6Pase in liver from the patient immediately after biopsy by the method of Nordlie and Arion gave low activity (0.8 mumol/min per g liver) in the absence of detergent, but was normal (10.2 mumol/min per g liver) after addition of detergent. Liver stored for a day at -25 degrees C had normal activity (3.4 mumol/min per g liver) without detergent. In patients with GSD Type la, G6Pase activity was very low both with and without detergent. These findings suggest a defect in glucose-6-phosphate transport in the microsomal membrane of the patient's liver. The integrity of microsomal membrane was destroyed by storage at -25 degrees C, when activity of G6 ase in the patient's liver could be demonstrated. This may be the first example of a disorder involving the transport system of an intracellular membrane.