Glycogen storage diseases (GSDs) are a group of inherited inborn errors of metabolism characterized by the deficiency of any one of the enzymes involved in glycogen metabolism, and subsequent build-up of excessive levels of glycogen in the body tissues. GSD I is caused by deficiency of the glucose 6 phosphatase or glucose 6 phosphate translocase enzyme. The cardinal features of this disorder are post absorptive hypoglycemia, lactic acidosis, hypertriglyceridemia, and hyperuricemia.
About 25% of all GSD cases are due to GSD I. Worldwide, the incidence of this disorder is estimated at about 1 affected patient in every 100,000 to 200,000 live births.