Infants at high risk for maple syrup disease (MSD) were identified by family history and molecular testing for the Y393N mutation of the E1a subunit of the branched chain a-ketoacid dehydrogenase in a study at Johns Hopkins University School of Medicine, Baltimore, MD. Eighteen neonates with MSD were identified in the high-risk group (n=39) between 12 and 24 hours of age using amino acid analysis of blood specimens. Eighteen additional infants, biochemically intoxicated at diagnosis, recovered rapidly with treatment emphasizing enhancement of protein anabolism and dietary correction of amino acid imbalances. Plasma leucine levels decreased to <400 mcmol/L at 2 to 4 days after diagnosis. Infections caused loss of metabolic control, with cerebral edema, hyponatremia and decreased osmolarity in 4 patients, but all recovered and developmental outcomes were good. 
COMMENT. The authors describe a treatment program for MSD that provides a benign neonatal course, normal growth and development, and management without hospitalization. Common infection may provoke metabolic intoxication with cerebral edema and hyponatremia. Treatment must inhibit protein catabolism, sustain protein synthesis, prevent amino acid deficiencies, and maintain normal serum osmolarity.