Hers disease is a genetic metabolic disorder caused by a deficiency of the enzyme, liver phosphorylase. This enzyme is necessary to break down (metabolize) glycogen, a carbohydrate that is stored in the liver and muscle and used for energy. Deficiency of this enzyme results in the abnormal accumulation of glycogen in the body. Hers disease is one of a group of disorders known as the glycogen storage disorders. It is characterized by enlargement of the liver (hepatomegaly), moderately low blood sugar (hypoglycemia), elevated levels of acetone and other ketone bodies in the blood (ketosis), and moderate growth retardation. Symptoms are not always evident during childhood, and children are usually able to lead normal lives.
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