Glycogen storage disease type VI

Glycogen

Glycogen storage disease type VI (GSD VI), also known as Hers disease, is a genetic disorder that affects the body's ability to break down glycogen into glucose. This condition is part of a group of disorders known as glycogen storage diseases, which result from defects in the processing of glycogen synthesis or breakdown within the body.

Pathophysiology

GSD VI is caused by a deficiency in the enzyme glycogen phosphorylase (also known as liver phosphorylase), which is crucial for the degradation of glycogen in the liver. This enzyme deficiency leads to the accumulation of glycogen in the liver, resulting in hepatomegaly (enlarged liver) and other related symptoms.

Genetics

GSD VI is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the defective gene, one from each parent, to be affected by the disorder. The gene responsible for GSD VI is the PYGL gene, which provides instructions for making the liver phosphorylase enzyme.

Symptoms

The symptoms of GSD VI can vary widely among affected individuals but often include:

• Hepatomegaly
• Hypoglycemia (low blood sugar)
• Growth retardation
• Ketosis
• Mild muscle weakness

Diagnosis

Diagnosis of GSD VI typically involves a combination of clinical evaluation, biochemical tests, and genetic testing. Liver biopsy may be performed to measure enzyme activity and confirm the diagnosis.

Treatment

There is no cure for GSD VI, but treatment focuses on managing symptoms and preventing complications. This may include:

• Frequent meals high in carbohydrates to maintain blood sugar levels
• Cornstarch therapy to provide a slow-release form of glucose
• Monitoring and managing ketosis

Prognosis

The prognosis for individuals with GSD VI is generally good, especially with proper management of the condition. Most individuals can lead normal lives with appropriate dietary adjustments and medical care.

Related Pages

• Glycogen storage disease
• Glycogen storage disease type I
• Glycogen storage disease type II
• Glycogen storage disease type III
• Glycogen storage disease type IV
• Glycogen storage disease type V
• Hypoglycemia
• Hepatomegaly

See Also

• Metabolic disorder
• Genetic disorder
• Enzyme deficiency

External Links

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