Glycogen Storage Disease, Type III (Cori’s Disease or Forbes disease)

Sephardi Disorders

Glycogen is one of the primary fuel reserves for the body’s energy needs. Stores of hepatic glycogen serve as a reserve for blood glucose during times of fasting and muscle glycogen serves as a reserve for substrates needed for ATP production during exercise. In glycogen storage disease, type III (GSD III), liver and/or muscle are unable to completely break down the stored glycogen to glucose, which is needed for energy production. Individuals with GSD III may develop hypoglycemia (low blood sugar) with fasting, and will typically have enlargement of the liver because of glycogen accumulation there. In addition, some individuals have muscle weakness affecting the skeletal and/or cardiac muscle. This is the result of deficiency of the debrancher enzyme involved in glycogen metabolism in liver and muscle.

Disease frequency	GSD III occurs in 1 in 5400 North-African Jews and in 1 in 200,000 in the general population.
Carrier frequency:	Estimated to be 1 in 35 in North African Jews.
Diagnosis:	By a physician knowledgeable about the disorder and by measuring the debrancher enzyme activity levels in leukocytes, a liver biopsy, or cultured skin fibroblasts.
Inheritance:	Autosomal recessive
Carrier testing:	Only in a family with known causative mutations.
Prenatal diagnosis:	Available to those with a previously affected child and if the mutations in the family are known.

Technical Information on Glycogen Storage Disease, Type III

Additional Information:
Association for Glycogen Storage (AGSD)
PO Box 896
Durant, IA 52747-9769
(563) 785-6038
www.agsdus.org