The term Glycogen Storage Disorder is used to describe a collection of genetic diseases that affect how glucose is converted to glycogen or how glycogen is broken down into glucose. There are more than 12 types of Glycogen Storage Disorder with each being caused by a different defective enzyme or the lack of a particular enzyme. The 10 most common types of Glycogen Storage Disorder are:
- Von Gierke’s disease – Type Ia
- Pompe’s disease –Type II
- Forbes-Cori disease – Type III
- Andersen’s disease – Type IV
- McArdle’s disease – Type V
- Hers’ disease – Type VI
- Tarui’s disease – Type VII
- Liver phosphorylase kinase deficiency – Type IX
- Fanconi-Bickel syndrome – Type XI
- Lewis’ disease – Type 0
Who is at Risk?
Glycogen Storage Disorders are extremely rare. As few as one in 40,000 infants are born with the genetic condition. Children born to parents carrying a recessive form of the altered gene have a 25-percent chance of developing an active Glycogen Storage Disorder. There is a 25-percent chance children are born with normal genes and a 50-percent chance children are born as carriers with no symptoms. In order for a child to be born with a Glycogen Storage Disorder, both parents typically need to be carriers of the affected gene, however, there is an inheritance pattern resulting from only one affected gene. If the mother is the carrier of an abnormal chromosome, she may pass an active form of the disease on to male children.
Typically, symptoms of Glycogen Storage Disorder are localized to muscles and the liver. Symptoms may include:
- Abnormally slow growth
- Enlarged liver
- Weak muscles
- Bleeding problems
- Clotting problems
- Kidney problems
- Achy muscles
- Reduced immune system
Not all patients with experience all symptoms. Some symptoms are more prominent in specific types of the disorder.
Doctors will start the diagnostic procedure with a detailed family history. Glycogen Storage Disorder is a genetic disease, so there may be a known family member diagnosed with the condition. If the family history leads the doctor to believe Glycogen Storage Disorder could be the condition, a series of tests may be ordered to rule out other conditions or verify the diagnosis.
Tests may include:
- Blood tests – Patients are tested for healthy liver and kidney function and blood glucose levels, among other factors that may be affected by the disorder.
- Ultrasound scans – May be used to view the liver and heart.
- Echocardiogram – Used to determine heart health.
There is no cure for Glycogen Storage Disorder, so treatments are based on controlling symptoms. Treatments may be ordered to control blood glucose, improve immunity and replace enzymes. Doctors may order a high protein diet, nutritional supplements and/or medications.
The affect on life expectancy with Glycogen Storage Disorder depends on the type and severity of the disease. In some cases, the severity of the disease leads to heart, liver and breathing problems, which can cause early death.