[Leucinosis: study of a case].

Report of a case of Maple syrup urine disease in a female neonate, with diagnosis at 26th day of life. The neurological picture consisted of alternating periods of hyper with hypotonicity, seizures, lethargy, poor feeding and respiratory arrest. Demonstration of elevation of plasma branched-chain amino-acids, was the most widely available confirmatory test, and the therapy with MSUD resulted in improvement of the patient.