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Glycogen storage disease due to liver glycogen phosphorylase deficiency

Synonym(s) GSD due to liver glycogen phosphorylase deficiency
GSD type 6
GSD type VI
Glycogen storage disease type 6
Glycogen storage disease type VI
Glycogenosis due to liver glycogen phosphorylase deficiency
Glycogenosis type 6
Glycogenosis type VI
Hepatic glycogen phosphorylase deficiency
Hepatic phosphorylase deficiency
Hers disease
Liver glycogen phosphorylase deficiency
Prevalence Unknown
Inheritance Autosomal recessive
Age of onset Childhood
  • E74.0
  • C0017925
MeSH -
  • 10053240


Disease definition

Liver phosphorylase deficiency, or glycogen storage disease type 6b (Hers' disease, GSD 6b) is a benign and rare form of glycogen storage disease.

Clinical description

The disease usually occurs in childhood and is characterized by hepatomegaly and growth delay. Hypoglycemic episodes are mild or absent, and hypertransaminasemia and hyperlipidemia are moderate and unconstant. Hepatomegaly usually improves with age and disappears entirely at puberty.


Transmission is autosomal recessive and mutations in the PYGL gene (14q21-q22) have been identified in patients.

Diagnostic methods

Diagnosis is based on biochemical findings revealing excess glycogen and partial deficiency of total and active phosphorylase in liver biopsy.

Management and treatment

A diet with high carbohydrate intake and regular meals prevents hypoglycemia in children, but most patients require no specific treatment.


Prognosis is usually good.

Expert reviewer(s)

  • Dr Roseline FROISSART

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Detailed information

Article for general public
Clinical genetics review
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