This form cannot be clinically differentiated from classic galactosemia. Although patients respond well to a lactose-restricted diet, some galactose intake is critical to ensure a supply of UDPgalactose for various metabolic processes. A group of hereditary disorders caused by lack of one or more enzymes involved in glycogen synthesis or breakdown and characterized by deposition of abnormal amounts or types of glycogen in tissues. Inheritance is autosomal recessive for all forms except GSD VI, which follows an X-linked inheritance. Symptoms and signs arise through accumulation of glycogen or other intermediate metabolites or through lack of an end product of glycogen breakdown, particularly glucose.
Diagnosis is confirmed by biopsy showing absence of the specific enzyme in affected tissue.
Treatment of GSD involving predominantly the liver is directed toward preventing hypoglycemia and lactic acidosis by implementing frequent small carbohydrate feedings. Uncooked cornstarch provides a steady blood glucose level and reduces lactic acidemia, hyperuricemia, and hyperlipidemia, which may allow catch-up growth. Alternatively, continuous overnight nasogastric feeding can provide glucose. GSD IV has been treated with liver transplantation. Allopurinol may be needed to prevent gout and renal urate calculi.