Maple Syrup Urine Disease, With Particular Reference to Dietotherapy

Our experiences with 7 patients with maple syrup urine disease are described. 2. It has been shown that the abnormal biochemistry and the neurological manifestations of maple syrup urine disease can be controlled by a diet low in the branched chain amino acids—leucine, isoleucine, and valine. If control is instituted sufficiently early, there is evidence that mental defect can be prevented. 3. A fourth abnormal amino acid, formerly thought to be methionine, has now been identified as alloisoieucine and evidence has been obtained that this is formed from isoleucine. Indications for restricting the methionine intake no longer exist. 4. Some of the hazards of dietotherapy in this disease are discussed, among them the existence of an unknown nutritional factor which is deficient in synthetic diets containing all the known dietary essentials. 5. The limitations of exchange transfusion for the immediate initial therapy of the disease are pointed out.