GSD type 0

Glycogen Storage Disease Type 0 (GSD Type 0) is a rare genetic disorder affecting glycogen metabolism. Unlike other forms of Glycogen Storage Disease which involve the accumulation of glycogen in various tissues, GSD Type 0 is characterized by a deficiency in the production of glycogen. This condition leads to issues with maintaining normal blood sugar levels, particularly during fasting periods.

Causes

GSD Type 0 is caused by mutations in the GYS2 gene, which encodes the liver isoform of glycogen synthase. This enzyme is crucial for the synthesis of glycogen from glucose. Mutations in the GYS2 gene result in reduced or absent activity of glycogen synthase, leading to the inability to form glycogen in the liver. GSD Type 0 is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to be affected by the disorder.

Symptoms

The primary symptom of GSD Type 0 is hypoglycemia (low blood sugar levels), especially after periods of fasting. Other symptoms may include:

• Ketosis - the presence of high levels of ketones in the blood, which can occur when the body breaks down fats for energy due to the lack of available glucose.
• Growth retardation - children with GSD Type 0 may experience slower growth rates.
• Fatigue and weakness due to the body's inability to utilize glucose efficiently for energy.

Diagnosis

Diagnosis of GSD Type 0 involves a combination of clinical evaluation, blood tests, and genetic testing. Blood tests may show low blood sugar levels and elevated ketone levels. Genetic testing can confirm the presence of mutations in the GYS2 gene.

Treatment

Management of GSD Type 0 focuses on preventing hypoglycemia. This may involve:

• Frequent meals and snacks to provide a steady supply of glucose.
• A high-carbohydrate diet to increase glucose availability.
• Cornstarch therapy, which provides a slow-release form of glucose, may be recommended, especially at night to prevent hypoglycemia during sleep.

Prognosis

With appropriate management, individuals with GSD Type 0 can lead normal lives. However, careful monitoring of blood sugar levels and adherence to dietary recommendations are crucial to prevent hypoglycemia and its associated complications.