<< Back to Infosheets

Type 1 Glycogen Storage Disease

The are various types of glycogen storage diseases, based on the symptoms, cause of enzyme deficiency and the organs involved. An important development in diagnosis was the isolation of the gene responsible of encoding the deficient enzyme. In the United States, molecular diagnosis in many families is possible an alternative to a biopsy of the liver in some cases. It also facilitated diagnosis in prenatal cases where there has previously been a sibling affected.

There are two subtypes of type 1 glycogen storage disease (GSD): Type 1a and Type 1b. The most common is Type 1a, resulting from deficiency of the glucose-6-phosphatase enzyme which helps maintain normal blood sugar levels during fasting periods. The patients usually have severe symptoms during early infancy which include low blood sugar (hypoglycemia), growth retardation, and an extremely enlarged liver (hepatomegaly). Although these individuals generally show normal liver function tests, they may have episodes of epistaxis (nosebleeds) or bleeding due to platelet dysfunction. Other blood abnormalities brought on by this disease are low glucose levels, elevated lactic and uric acids, and elevated cholesterol and triglycerides counts.

Patients with less common form of GSD, Type 1b, in addition to the symptoms indicated also have low white blood cell counts (neutropenia) with episodes of infections. Type 1b GSD is caused by an abnormality in translocase enzyme activity within the cells.

Late complications that can develop with this disease are benign and cancerous liver tumors, problems with kidneys, and fractures due to osteopenia. It is uncertain whether appropriate medical treatment in childhood would prevent some of these complications, but the management of hypoglycemia in infancy has resulted in long-term survival for these patients.

Treatment:

Patients are generally fed frequently and supplemented by nasal glucose infusions during the night or uncooked cornstarch orally 4 to 6 times a day. The purpose of this special diet is to achieve and maintain normal blood sugar levels. Sugars commonly found in many foods, such as fructose, lactose and galactose, which are converted to glucose-6-phospate in the liver, are avoided also. To reduce bleeding complications in patients with Type 1b, serious infections and neutropenia are treated with the drug GCSF. Another platelet enhancing drug, DDAVP, also reduces bleeding complications when used prophylactically prior to surgery.

© Copyright 2000 - Latino Organization for Liver Awareness / Revised: March 2009