Genetic disease characterized by excess hepatic glycogen due to a mutation in the gene for hepatic phosphorylase.
Hers disease, glycogen storage disease VI, is a hereditary glycogen storage disease caused by a deficiency of the enzyme called liver phosphorylase. Typically seen in children between the ages of 1 and 5, Hers disease sometimes goes undiagnosed until adulthood. The most prominent symptom of Hers disease is an enlarged liver. This anomaly occurs as a result of low-level phosphorylase’s inability to break down glycogen into glucose, thus causing the glycogen to accumulate in the liver, resulting in the enlargement of the liver.