Glycogen debrancher deficiency

Glycogen Debrancher Deficiency Glycogen Debrancher Deficiency, also known as Glycogen Storage Disease Type III (GSD III), is a rare genetic disorder that affects the body's ability to break down glycogen, a stored form of glucose. This condition is caused by a deficiency in the enzyme amylo-1,6-glucosidase, 4-alpha-glucanotransferase, which is responsible for the debranching of glycogen during glycogenolysis.

Pathophysiology

Glycogen debrancher deficiency results in the accumulation of abnormally structured glycogen in the liver and muscles. This accumulation leads to hepatomegaly, hypoglycemia, and muscle weakness. The enzyme deficiency affects the liver, muscles, and sometimes the heart, leading to a range of symptoms.

Clinical Presentation

Patients with GSD III typically present with:

• Hepatomegaly: Enlarged liver due to glycogen accumulation.
• Hypoglycemia: Low blood sugar levels, especially during fasting.
• Muscle Weakness: Due to glycogen accumulation in muscle tissues.
• Growth Retardation: Delayed growth in children.

Diagnosis

Diagnosis of Glycogen Debrancher Deficiency involves:

• Biochemical Tests: Blood tests showing hypoglycemia and elevated liver enzymes.
• Genetic Testing: Identification of mutations in the AGL gene.
• Liver Biopsy: Histological examination showing glycogen accumulation.

Treatment

Management of GSD III focuses on dietary modifications and supportive care:

• Dietary Management: Frequent meals rich in carbohydrates to prevent hypoglycemia.
• Cornstarch Therapy: Uncooked cornstarch to maintain blood glucose levels.
• Monitoring: Regular follow-up to monitor liver function and muscle strength.

Prognosis

The prognosis for individuals with Glycogen Debrancher Deficiency varies. With proper management, many individuals can lead relatively normal lives, although some may experience progressive muscle weakness and liver complications.

Genetics

GSD III is inherited in an autosomal recessive pattern. Mutations in the AGL gene are responsible for the enzyme deficiency. Genetic counseling is recommended for affected families.

Research and Future Directions

Ongoing research aims to better understand the molecular mechanisms of GSD III and develop potential therapies, including enzyme replacement therapy and gene therapy.

See Also

• Glycogen Storage Disease
• Metabolic Disorders
• Enzyme Deficiencies

NIH genetic and rare disease info

• NIH info on Glycogen debrancher deficiency

Glycogen debrancher deficiency is a rare disease.