| Abstract: | Leukocytes and skin fibroblasts from a patient with classical maple syrup urine disease (M.S.U.D.) contained virtually no branched-chain keto acid decarboxylase activity. Those of his parents had approximately 50 % of normal activity, and those of his sister had normal activity. The patient was treated from the second week of life with a “synthetic diet”. At the age of 2 months, when the patient was completely free of symptoms, 20 mg of thiamine three times daily was given orally. On the second day of treatment, he was challenged with cow's milk. Within 12 hours he became irritable; within 24 hours he refused feeding and his urine had the characteristic odor of M.S.U.D. The symptoms became more marked with progressive increase of plasma branched-chain amino acids. This classical M.S.U.D., like the intermediate type, did not respond to thiamine Iherapy. |
