Glycogen storage disease type IX

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Glycogen storage disease type IX
Synonyms	GSD IX
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Specialty	Endocrinology, Genetics
Symptoms	Hypoglycemia, hepatomegaly, growth retardation
Complications	N/A
Onset	Infancy or childhood
Duration	Chronic
Types	N/A
Causes	Genetic mutation in PHKA2, PHKB, or PHKG2 genes
Risks	Family history
Diagnosis	Genetic testing, liver biopsy
Differential diagnosis	Glycogen storage disease type VI, Glycogen storage disease type III
Prevention	N/A
Treatment	Dietary management, cornstarch therapy
Medication
Prognosis	Generally good with treatment
Frequency	1 in 100,000
Deaths	Rare

Microscope with stained slide

Glucose Fisher to Haworth

Glycogen storage disease type IX (GSD IX) is a metabolic disorder that results from a deficiency of an enzyme involved in glycogen synthesis. This disease is part of a larger group of diseases known as Glycogen storage diseases.

Symptoms

The symptoms of GSD IX typically appear in early childhood and can vary in severity. Common symptoms include hepatomegaly (enlarged liver), hypoglycemia (low blood sugar), ketosis (excess of ketone bodies in the body), hyperlipidemia (high levels of fats in the blood), and growth retardation. Some individuals may also have xanthomas (fatty deposits under the skin) due to high levels of fats in the blood.

Causes

GSD IX is caused by mutations in the PHKA2, PHKB, and PHKG2 genes. These genes provide instructions for making different subunits of the phosphorylase kinase enzyme, which is involved in the breakdown of glycogen. Mutations in these genes reduce the activity of this enzyme, preventing the normal breakdown of glycogen and leading to the symptoms of GSD IX.

Diagnosis

The diagnosis of GSD IX is based on the clinical symptoms, laboratory findings (including abnormal liver function tests and low blood sugar), and confirmed by genetic testing. A liver biopsy may also be performed to examine the amount and structure of glycogen in the liver.

Treatment

There is no cure for GSD IX. Treatment is focused on managing the symptoms and preventing complications. This may include a high-protein diet to prevent low blood sugar, medications to control high levels of fats in the blood, and regular monitoring of liver function.

Prognosis

The prognosis for individuals with GSD IX varies. Some individuals have mild symptoms and normal growth and development, while others may have severe symptoms and complications such as liver disease.

See also

• Glycogen storage disease
• Metabolic disorders
• Hepatomegaly
• Hypoglycemia
• Ketosis
• Hyperlipidemia
• Xanthomas