What is GSD?
Glycogen Storage Disease (GSD) is a rare group of inherited/genetic diseases that inhibit the body from properly using stored energy known as glycogen.
Because there are a number of different enzymes involved in glycogen production and breakdown, there are a number of different types of GSD.
- Type Ia (von Gierke’s disease), type Ib.
- Type II (Pompe’s disease).
- Type III (Forbes-Cori disease).
- Type IV (Andersen’s disease).
- Type V (McArdle’s disease).
- Type VI (Hers’ disease).
- Type VII (Tarui’s disease).
- Type IX (liver phosphorylase kinase deficiency).
- Type XI (Fanconi-Bickel syndrome).
- Type 0 (Lewis’ disease).
GSD Type I is the most common form of GSD and it is often said that it is the most severe.
People with GSD Type I are able to store glucose as glycogen but unable to release it normally.
Imagine that you go to the grocery store and stock up on all your favorite foods. You bring them home and put them away in your pantry. A few hours later when you start to get hungry you decide to head to the pantry to look for your favorite snack. You try to open it up but you can’t get it open to get the food that you want. This is what happens to glucose with people who have GSD I. They can store it in the liver as glygocen, but they can not access it later for energy once it is in there.
This results in severe hypoglycemia (low blood sugar) and the inability for those with GSD I to be able to maintain normal blood sugar levels on their own. They rely on frequent feeds and/or cornstarch boluses to keep their blood sugar levels in a safe zone. With out these, blood sugar levels drop very quickly to a dangerous level and can result in seizures, brain damage or even death.
Children with GSD Type I are usually diagnosed as infants when the time between feeds starts to get spaced out and the infant starts to sleep through the night. They often present with low blood sugar, high levels of lipdis and uric acid in the blood stream, an enlarged liver and a swollen abdomen. They also may have a progressive decrease in growth, delayed motor development and a “doll-like” face with excess fat in the cheeks.
Today children can be diagnosed by non-invasive genetic testing along with complementary blood tests. A liver biopsy is no longer required to diagnose GSD.
Because of advances in science, GSD patients are living longer, healthier lives but they continue to struggle to feel like everyone else. Most patients must drink a solution of cornstarch and water every 3-4 hours around the clock. Infants often can not tolerate and digest cornstarch so they rely on frequent feeds of a soy or dairy free formula. Many patients with GSD have a gastrostomy tube (g-tube) surgically placed in their stomach to allow for quick access for food, glucose, cornstarch or other medicines. Patients with GSD also must not consume most fruit, milk, and sugars.
Living with GSD or caring for someone with GSD can be stressful and exhausting. Constant monitoring, feeding and administering cornstarch boluses is an around the clock job.
We are hopeful that research will continue to move forward so that markers for GSD will be able to be identified in the blood and that GSD will be able to be included on the newborn blood screen. This way life threatening events and even early deaths due to undiagnosed GSD can be avoided. We are also hopeful for a cure and know that it can happen in our lifetime.
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