Glycogen Storage Disease, Type Ib (SLC37A4)
Glycogen storage disease, type Ib is a pan-ethnic, autosomal recessive disease caused by pathogenic variants in the gene SLC37A4. GSD1b affects the bodys ability to convert food into energy, meaning that affected individuals easily develop hypoglycemia (low blood sugar). Symptoms begin at around 3-4 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 live into adulthood. It is not currently possible to predict how severe the disease will be based on the inherited variants.
For information about carrier frequency and residual risk, please see the residual risk table.