Glycogen Storage Disease | Symptoms & Causes

What causes glycogen storage disease?

GSD is an inherited disease. Children are born with GSD when both parents have an abnormal gene that gets passed on to one of their children. The parents typically don’t have the disease or any of its symptoms.

Children with GSD lack one of the enzymes responsible for converting glycogen to glucose. As a result, their muscles do not receive the fuel they need to grow and glycogen builds up in their liver and other organs.

What are the symptoms of glycogen storage disease?

Symptoms of glycogen storage disease (GSD) typically appear early, when a child is still a baby or very young child.

Though symptoms vary depending by type of GSD, the following symptoms are common:

  • delayed growth
  • heat intolerance
  • easy bruising
  • swollen belly
  • weak muscles
  • muscle pain and cramping
  • chronic hunger
  • irritability

What are the risks of GSD?

Each type of GSD carries specific risks.

Infants with type I (GSD I) may have low blood sugar, which increases their risk for seizures. This type of GSD can also lead to lactic acidosis, a build up of lactic acid, which can cause painful muscle cramps. As they mature into adolescence, children with GSD I may have delayed puberty and weak bones (osteoporosis). Other risks include:

Infants with type III (GSD III) may have low blood sugar and excess fat in their blood. As they get older, their livers may become enlarged. Some children’s livers go back to a normal size when they hit adolescence but others develop cirrhosis and liver failure. Children with this type of GSD are also at risk for:

  • slow growth and short stature
  • muscle weakness

Type IV (GSD IV) is often fatal for newborns and infants. Children who survive with GSD IV are at risk for the following complications: