Glycogen Storage Disease Type IV

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Glycogen Storage Disease Type IV is caused by a problem in the GBE1 gene. The GBE1 gene provides instructions for making something called the glycogen branching enzyme. This glycogen branching enzyme produces glycogen. Glycogen is a major source of stored energy in your body and what your body partly uses for fuel.

Problems in the GBE1 result in a shortage of glycogen branching enzymes, this means that glycogen is not formed properly. The deformation of the glycogen molecules results in the glycogen molecules building up in cells, causing damage and killing cells. This process happens throughout your body; however, your liver and muscles cells will be most affected. The inability of muscle cells to break down glycogen for energy, results in the muscle becoming weak and wasting.

There are 5 types of GSD4; perinatal neuromuscular type, congenital muscular type, progressive hepatic type, non-progressive hepatic type, childhood neuromuscular type.

GSD4 is estimated to occur in 1 in 600,000 to 800,00 people worldwide. It is believed to account for 3% of all glycogen disorder cases.

Fatal Perinatal Neuromuscular Type:

• Signs typically develop before birth
• Excess fluid may build up around the foetus and in the foetus’ body.
• Decrease in foetal movement leading to joint stiffness after birth.
• Low muscle tone in infants.
• Often fatal due to a weakened heart and breathing muscles.

Congenital Muscular Type:

• Typically develops in early infancy.
• Difficulties breathing
• Enlarged and weakened heart
• Infants with GSD4 Congenital Muscular Type typically only survive a few months.

Progressive Hepatic Type

• Most common form of GSD4.
• Difficulty gaining weight and growing at expected rate.
• Enlarged liver.
• Irreversible liver disease (cirrhosis)
• High blood pressure
• Children with GSD 4 Progressive Hepatic type typically don’t survive past early childhood.

Non-progressive Hepatic Type

• Not as severe as GS4 Progressive type.
• Liver disease evident in early childhood
• Muscle weakness
• Patients with GSD4 non-progressive hepatic type, typically survive into adulthood.

Childhood Neuromuscular Type

• Develops in late childhood and severity varies greatly.
• Mild muscle weakness
• Severe muscle weakness which can be fatal.

GSD4 is usually diagnosed or confirmed after birth, during infancy or childhood. There have been some cases of diagnosis being made during adulthood. Patients are often diagnosed via tissue biopsies, a physical examination, family and patient history, blood tests, abdominal ultrasound, CT scanning, and/or MRI and an echocardiography).

In some cases, GSD4 can be diagnoses before birth via specialised tests. These tests usually involve a sample of fluid surrounding the foetus being taken and/or a small sample of tissue being taken from the placenta.

GSD4 patients are often treated by a multidisciplinary team and treatment is directed towards specific symptoms. Treatment may require a coordinated approach by a team of professionals such as paediatricians, specialists or treat the digestive tract, neurologists, cardiologists, dieticians and/or other health care professionals.

Patients suffering from liver disease, neuromuscular disease and/or heart issues will often require long term treatment. Some treatment may also require input from a specialist dietician who will provide a specialist diet. Patients suffering with heart weakness may be given medications to treat heart failure and may require surgery.

Patients living with GSD4 may suffer from liver disease, therefore in these instances a liver transplant will be considered.

At present there is no clinical trial relating to the treatment of GSD4 taking place, however Duke University in North Carolina USA are currently compiling a patient registry of GSD4 patients, this research will end in 2025. If you are interested in taking part, please contact Metabolic Support UK for further information.

If you or someone you know has been affected by GSD4 you may want to consider genetic counselling, you will need to speak to you GP or metabolic specialist for a referral to a genetic counsellor. If you would like more information about genetic counselling, a toolkit can be found on the Metabolic Support UK website.

Glycogen storage disease type IV is an inherited condition. Humans have chromosomes made up of DNA. Genes are pieces of DNA that carry the genetic information. Each chromosome may have several thousand genes. We inherit chromosomes from the egg of the mother and sperm of the father. The genes on those chromosomes carry the instructions that determine a person’s characteristics, which are a combination of the parents.  

The pattern of inheritance of glycogen storage disease type IV is autosomal recessive. This means that carriers of the condition do not have the disorder because the other gene of this pair is working normally. Parents of children with glycogen storage disease type XI are carriers.   

When both parents are carriers, the risk to the baby in each pregnancy is  

• 25% chance (1 in 4) of developing the condition  
•  50% chance (1 in 2) for the baby to be a carrier of the condition  
•  25% chance (1 in 4) for the baby to have two working genes and neither have the condition nor be a carrier  

Genetic counselling can be requested to get a full explanation.

For more information, please visit Association for Glycogen Storage Disease UK.

References are available on request. Please contact Helen Morris by phoning 0845 241 2173 or emailing helen@metabolicsupportuk.org [Resource Library No: AAP002].