What Is GSD?

Glycogen Storage Disease (GSD) is a group of rare inherited metabolic disorders caused by enzyme deficiencies that affect the body's ability to store or release glycogen — the stored form of glucose used as fuel for energy. When these enzymes are absent or deficient, glycogen accumulates abnormally in cells, primarily in the liver and/or muscles.

GSD primarily affects the liver and/or muscles, though some types can impact the heart, kidneys, and other organs. Symptoms vary widely depending on the type of GSD and can include low blood sugar (hypoglycaemia), muscle weakness, enlarged liver, growth delays, and exercise intolerance. Many types of GSD are diagnosed in infancy or early childhood, though some are not identified until adulthood.

There are more than a dozen distinct types of GSD, each caused by a deficiency in a specific enzyme involved in glycogen metabolism. While there is currently no cure for most types of GSD, management strategies — including dietary therapy, enzyme replacement therapy, and emerging gene therapies — can significantly improve quality of life and long-term outcomes for patients and families.