Glycogen Storage Disease, Type Ia (G6PC)
Glycogen storage disease type 1a (GSD1a) is an autosomal recessive disease caused by pathogenic variants in the gene G6PC. GSD1a affects the bodys ability to convert food into energy, meaning that affected individuals easily become hypoglycemic (low blood sugar). Symptoms begin at around 3 to 4 months of age with hypoglycemia, enlarged liver, and seizures. Treatment with frequent feedings and a carefully controlled diet greatly reduces symptoms of the disease, which may include seizures, stunted growth, enlarged liver, and irritability when untreated. Untreated hypoglycemia is dangerous and can be fatal, but with lifelong treatment affected individuals can live into adulthood. It is not currently possible to predict how severe the disease will be based on the type of pathogenic variant inherited. GSD1a can affect people of any ethnicity, but it is more common in people of Ashkenazi Jewish descent.
For information about carrier frequency and residual risk, please see the residual risk table.