Type I glycogen storage disease (GSD I), also known as von Gierke’s disease, is the most common form of glycogen storage disease, accounting for 25% of all cases. It is an inherited disorder that affects the metabolism – the way the body breaks food down into energy.
After we eat, excess glucose is stored in the liver as glycogen to maintain normal glucose levels in our body. In GSD I, the enzyme needed to release glucose from glycogen is missing. When this occurs, a person cannot maintain his or her blood glucose levels and will develop hypoglycemia (low blood sugar) within a few hours after eating. The low levels of glucose in the blood of these individuals often result in chronic hunger, fatigue, and irritability. These symptoms are especially noticeable in infants.
Since people with GSD I are able to store glucose as glycogen but unable to release it normally, stores of glycogen build up in the liver over time and cause it to swell. The liver is able to perform many of its other functions normally, and there is no evidence of liver failure. The kidneys also become enlarged because of increased glycogen storage.