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Glycogen Storage Disease, Type 0
Sunday, 14 August 2005
Sunday, 14 August 2005
Liver Glycogen Synthase Deficiency

What

Glycogen Storage Disease is a family of genetic diseases involving the metabolism of glycogen (a big sugar molecule) in the body. It has numerous types, each with its own symptoms and characteristics. Glycogen Storage Disease type 0 (GSD-0) is caused by a defective enzyme in the liver of the affected child. It often causes a large liver, morning fatigue and sometimes seizures. Undiagnosed or untreated, a severely affected child can have delayed growth and development, intellectual deficits, and personality changes.

Who

Frequency of glycogen storage disease is 1 in 20,000 to 25,000 internationally. Glycogen storage disease type 0 is a rare form of this family of diseases, accounting for 1% of all cases. It occurs equally in boys and girls and in all ethnic groups. The signs and symptoms of the disease tend to appear in infancy or early childhood.

Signs and Symptoms

Children with GSD-0 start showing symptoms of the disease when they go for long periods without eating, usually 5 hours or longer. Children with this disease often do not have problems early in infancy, but only after weaning from overnight feeds. Thus, most would have problems early in the morning, right after they wake up and/or before breakfast. Symptoms, due to low sugar in the blood (hypoglycemia), include drowsiness or jitteriness, lethargy, sweating, lack of attention or mental confusion, headache, nausea and vomiting, visual/gait/speech disturbances. In severe and prolonged episodes, the affected child can have seizures and go into a coma. Symptoms often are reversed with food. They often require frequent meals and snacks. Some children with this disease also have a large liver and may exhibit delayed growth (both height and weight).

Possible Causes

This disease is inherited in an autosomal recessive manner, meaning that an affected child received a mutated copy of the gene responsible for this disorder from each parent. Each parent would be a carrier of the gene for GSD-0 but not have symptoms; they would have one copy of the gene with a genetic change and a second copy that functions normally. The gene, known as glycogen synthase 2, responsible for this disorder makes a protein whose normal function is to make a big sugar molecule (glycogen) from small sugar molecules (glucose). Glycogen is a storage form of sugar and the body breaks it back down to glucose and uses it when needed, such as a couple hours after a meal. Thus, children with GSD-0 often have problems several hours after a meal because they do not have glucose for the brain to use.

Diagnosis

A liver biopsy (where a small piece of liver tissue is removed and analyzed) is often necessary to confirm the diagnosis of GSD-0. A blood test is also done to measure various compounds within the blood, such as sugar, lactate, and alanine. Sometimes a urine test is also performed.

Treatment

Treatment, with specialists such as a nutritionist, endocrinologist, geneticist and/or metabolic specialists, consists of frequent protein-rich meals, avoidance of fasting, and nighttime feedings of uncooked cornstarch.

Prognosis

Prognosis for children with GSD-0 is good with normal growth and intellectual development when the disease is diagnosed early and the diet recommended by specialists is followed.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

Association for Glycogen Storage Disease
Has a $20 annual membership fee. There is a newsletter, handbook, phone support, conference, and chat forum for emotional support for family affected with glycogen storage diseases. National Information and Advice Center for Metabolic Diseases. http://www.niacmd.net/ Has a member only chat forum for patients and families affected with metabolic diseases.

Google Search for Glycogen Storage Disease, Type 0

References and Sources

Lerardi-Curto, L. Glycogen Storage Disease Type 0. eMedicine. Oct 10, 2003. http://www.emedicine.com/ped/topic873.htm Craigen, W. Liver glycogen synthase deficiency (glycogen storage disease 0). UptoDate. http://www.utdol.com/application/topic.asp?file=dis_chld/9966&type=P&selectedTitle=3~5 OMIM. Glycogen Storage Disease 0. http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=240600