Glycogen Storage Disease
What is glycogen storage disease in children?
Glycogen storage disease (GSD) is a rare condition that changes the way the body uses and stores glycogen, a form of sugar or glucose.
Glycogen is a main source of energy for the body. Glycogen is stored in the liver. When the body needs more energy, certain proteins called enzymes break down glycogen into glucose. They send the glucose out into the body.
When someone has GSD, they are missing one of the enzymes that breaks down glycogen. When an enzyme is missing, glycogen can build up in the liver. Or glycogen may not form properly. This can cause problems in the liver or muscles, or other parts of the body.
GSD is passed down from parents to children (is hereditary). It is most often seen in babies or young children. But some forms of GSD may appear in adults.
Types of GSD
Types of GSD are grouped by the enzyme that is missing in each one. Each GSD has its own symptoms and needs different treatment.
There are several types of GSD, but the most common types are types I, III, and IV. These types are also known by other names:
- Type I or von Gierske disease. This is the most common form of GSD. People with type I don’t have the enzyme needed to turn glycogen into glucose in the liver. Glycogen builds up in the liver. Symptoms often appear in babies around 3 to 4 months old. They may include low blood sugar (hypoglycemia) and a swollen belly because of an enlarged liver.
- Type III, Cori disease, or Forbes disease. People with type III don’t have enough of an enzyme called the debranching enzyme, which helps break down glycogen. The glycogen can’t fully break down. It collects in the liver and in muscle tissues. Symptoms include a swollen belly, delayed growth, and weak muscles.
- Type IV or Anderson disease. People with type IV form abnormal glycogen. Experts think the abnormal glycogen triggers the body’s infection-fighting system (immune system). This creates scarring (cirrhosis) of the liver and other organs such as muscle and the heart.
What causes glycogen storage disease in a child?
Glycogen storage disease is passed down from parents to children (hereditary).
It happens because both parents have an abnormal gene (gene mutation) that affects a specific way that glycogen is stored or used. Most GSDs occur because both parents pass on the same abnormal gene to their children.
In most cases parents don’t show any symptoms of the disease.
Which children are at risk for glycogen storage disease?Glycogen storage disease is passed down from parents to children (inherited). Someone is more at risk for GSD if they have a family member with the disease.
What are the symptoms of glycogen storage disease in a child?
With many types of GSD, symptoms first appear in babies or in very young children. Symptoms will vary based on the type of GSD a child has, and on which enzyme he or she is missing.
Because GSD most often affects the muscles and the liver, those areas show the most symptoms.
General symptoms of GSD may include:
- Not growing fast enough
- Not feeling comfortable in hot weather (heat intolerance)
- Bruising too easily
- Low blood sugar (hypoglycemia)
- An enlarged liver
- A swollen belly
- Weak muscles (low muscle tone)
- Muscle pain and cramping during exercise
Symptoms for babies may include:
- Too much acid in the blood (acidosis)
- High blood cholesterol levels (hyperlipidemia)
The symptoms of GSD may look like other health problems. Always see your child’s healthcare provider to be sure.
Some types of GSD can appear in adults. See your healthcare provider if you think you may have GSD.
How is glycogen storage disease diagnosed in a child?
Your child’s healthcare provider will ask about your child’s symptoms and past health. The provider will do a physical exam to check for symptoms such as an enlarged liver or weak muscles.
Your child’s provider may do a few blood tests. He or she may also take a small tissue sample (biopsy) of your child’s liver or muscle. The sample will be taken to a lab. It will be tested to see how much of a certain enzyme is in that part of the body.
If you are pregnant and concerned about GSD, your healthcare provider may do some tests before your baby is born (prenatal tests) to check for GSD.
How is glycogen storage disease treated in a child?
Treatment will vary depending on what type of GSD your child has.
For types I, III, and IV, your child’s healthcare provider may suggest a special diet to help control symptoms. Your child may also have to take certain medicines.
For other types of GSD, your child may need to limit exercise to avoid muscle cramps. He or she may need to have a medical treatment to replace the enzyme that is missing (enzyme replacement therapy).
What are possible complications of glycogen storage disease in a child?
Glycogen buildup can hurt the liver and muscles. This can create other problems if your child has certain types of GSD such as:
- Type III. This can cause harmless (benign) tumors in the liver.
- Type IV. Over time this can cause scarring (cirrhosis) of the liver. This disease leads to liver failure.
What can I do to prevent glycogen storage disease in my child?
There is no way to prevent glycogen storage disease. But early treatment can help control symptoms once a child has GSD.
If you or your partner have GSD, or a family history of this disease, see a genetic counselor before you get pregnant. He or she can find out your chances of having a child with GSD.
How can I help my child live with glycogen storage disease?
A child with GSD may have special needs. Be sure that your child gets regular medical care. It is important that his or her healthcare provider checks your child’s condition. Regular medical visits will also help you keep up with new treatment options.
Online or in-person support groups may also be helpful for you and your family.
When should I call my child’s healthcare provider?
Many forms of glycogen storage disease appear in babies and young children.
Call your healthcare provider if your baby’s behavior changes after you stop night feedings.
Talk with your healthcare provider if your child:
- Is not growing fast enough
- Has constant (chronic) hunger
- Has a swollen belly
Teens and adults should watch for the following symptoms when they exercise:
- Muscle weakness
Key points about glycogen storage disease in children
- Glycogen storage disease (GSD) is a rare condition that changes the way the body uses and stores glycogen, a form of sugar.
- It is passed down from parents to children (inherited). For most GSDs, each parent must pass on one abnormal copy of the same gene.
- Most parents do not show any signs of GSD.
- There are several types of GSD, but types I, III, and IV are most common. Each GSD has its own symptoms and needs different treatment.
- Symptoms often first appear in babies or young children. In some cases GSD can appear in adults.
Tips to help you get the most from a visit to your child’s healthcare provider:
- Know the reason for the visit and what you want to happen.
- Before your visit, write down questions you want answered.
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
- Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
- Ask if your child’s condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if your child does not take the medicine or have the test or procedure.
- If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.