Glycogen storage disease type III

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
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Glycogen storage disease type III
Glycogen storage disease in liver
Synonyms	Cori disease, Forbes disease, Limit dextrinosis
Pronounce
Specialty	Endocrinology, Genetics
Symptoms	Hepatomegaly, hypoglycemia, muscle weakness
Complications	N/A
Onset	Childhood
Duration	Lifelong
Types	N/A
Causes	Genetic mutation in the AGL gene
Risks	Family history
Diagnosis	Genetic testing, liver biopsy
Differential diagnosis	Glycogen storage disease type I, Glycogen storage disease type II
Prevention	N/A
Treatment	Dietary management, cornstarch therapy
Medication
Prognosis	Variable, generally good with treatment
Frequency	Rare
Deaths

Autosomal recessive inheritance pattern

Alpha-D-glucopyranose 2D skeletal structure

Glycogen Storage Disease Type III (GSD III), also known as Cori disease or Forbes disease, is a rare genetic disorder that affects the metabolism of glycogen. It is one of the several types of glycogen storage diseases, which are characterized by the abnormal storage and accumulation of glycogen in the body.

Pathophysiology

GSD III is caused by a deficiency in the enzyme amylo-1,6-glucosidase, also known as the debranching enzyme. This enzyme is crucial for the proper breakdown of glycogen into glucose. In individuals with GSD III, the debranching enzyme is either absent or not functioning correctly, leading to the accumulation of abnormally structured glycogen in the liver and muscle tissues.

Clinical Features

The symptoms of GSD III can vary widely among affected individuals. Common clinical features include:

• Hepatomegaly (enlarged liver)
• Hypoglycemia (low blood sugar levels)
• Hyperlipidemia (elevated levels of lipids in the blood)
• Myopathy (muscle weakness)
• Growth retardation

Diagnosis

Diagnosis of GSD III is typically based on clinical evaluation, biochemical tests, and genetic testing. Liver biopsy may reveal the presence of abnormal glycogen deposits. Genetic testing can confirm mutations in the AGL gene, which encodes the debranching enzyme.

Treatment

There is currently no cure for GSD III, but treatment focuses on managing symptoms and preventing complications. Dietary management is crucial and may include:

• Frequent meals high in carbohydrates
• Avoidance of fasting
• Supplementation with cornstarch to maintain blood glucose levels

Prognosis

The prognosis for individuals with GSD III varies. With proper management, many individuals can lead relatively normal lives, although some may experience progressive muscle weakness and liver disease.

See also

• Glycogen storage disease
• Metabolic disorder
• Genetic disorder