The enzyme glycogen synthase is needed for the body to make glycogen. A deficiency results in very low amounts of glycogen stored in the liver. A person between meals can develop very low blood sugar levels, known as hypoglycemia. Early in infancy children usually have no symptoms. The hypoglycemia typically develops once night feeding stops. Before breakfast children may have drowsiness, look pale, have vomiting, fatigue and sometimes convulsions. If a GP investigates a child lacking energy, hypoglycemia is often discovered through morning urine samples.

Other names |
Glycogen synthase deficiency |
Affected |
Liver and muscle forms |
Inheritance | Autosomal recessive |
Incidence |
Less than 1 in 1,000,000 |
UK diagnosed | Unkown |
Symptoms |
Before breakfast drowsiness, tiredness, looking pale, vomiting. |
Secondary symptoms |
Quick to tire, muscle cramps |
Treatment |
Regular snacks, cornstarch to reduce overnight hypoglycemia. |
Outlook |
Good with adherence to recommended feeding. |
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