Management of maple syrup urine disease in Canada. Committee for improvement of Hereditary Disease Management.

Nine patients with classic maple syrup urine disease (MSUD) and four with variant forms are under care at five treatment centres in the network affiliated with the National Food Distribution Centre for the Treatment of Hereditary Metabolic Diseases (the "Food Bank"). Diagnosis was made by clinicians and not from mass screening programs. MSUD requires complex emergency treatment to prevent severe neurologic damage, but effective management is compatible with normal growth and development. Long-term treatment requires continuous monitoring of the response to diets restricted in branched-chain amino acids; semisynthetic diet products free of branched-chain amino acids, provided by the Food Bank, are essential. Centralized treatment programs reduce the cost of treatment and maximize the potential benefits. The leucine requirement for adequate somatic growth during infancy in MSUD was found to be 200 to 600 mg/d; this range is lower than that estimated for infants with an intact leucine catabolic outflow pathway. The requirements for isoleucine and valine in infancy were also found to be lower than published values for normal infants.