Glycogen storage disease

Glycogen storage diseases are inherited disorders caused by defects in glycogen synthesis or breakdown. They can cause glycogen to accumulate abnormally or leave tissues unable to access stored glucose.

Glycogen: A branched glucose polymer that animals store mainly in liver and muscle. Its storage and release are disrupted in these disorders.
Von Gierke disease: A glycogen storage disease caused by deficient glucose-6-phosphatase activity or glucose-6-phosphate transport. It illustrates severe fasting hypoglycemia from impaired hepatic glucose release.
Glucose-6-phosphatase: An enzyme that converts glucose-6-phosphate into free glucose, chiefly in liver and kidney. Its loss blocks the final step of hepatic glucose release in Von Gierke disease.
Newborn screening: Testing performed soon after birth to identify conditions for which early intervention can help. Screening can detect Pompe disease before severe symptoms develop.
Glycogen synthase deficiency: A disorder in which impaired glycogen synthesis causes fasting hypoglycemia and low glycogen stores. It is a glycogen storage disease in which too little, rather than excess, glycogen is stored.
Glycogenesis: The cellular pathway that builds glycogen from glucose. Defects in glycogen synthesis cause a subset of storage diseases.
Pompe disease: A lysosomal glycogen storage disease caused by deficiency of acid alpha-glucosidase. It differs from most forms by accumulating glycogen inside lysosomes.
Glycogen phosphorylase: An enzyme that releases glucose-1-phosphate from glycogen chains. Tissue-specific deficiencies explain liver and muscle forms with different symptoms.
Enzyme replacement therapy: Treatment that supplies a manufactured enzyme to compensate for deficient enzyme activity. It is an established treatment for Pompe disease.
Glycogenosis: A broad term for disorders involving abnormal glycogen metabolism or accumulation. It is often used as a synonym for glycogen storage disease.

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