MAPLE syrup disease is a rapidly progressive familial cerebral degenerative condition marked by the excretion of a urine possessing a sweet, maple syrup-like odor.1 The enzymatic basis for this disease is a failure in the oxidative decarboxylation of three branched-chain keto acids, the derivatives of leucine, valine, and isoleucine. As a consequence of the defect, these compounds and their amino acid analogues are excreted in large amounts, and plasma levels of branched-chain amino acids are many times higher than normal.2 Hypertonia, disturbances in respiration, and seizures appear shortly after birth and prove to be fatal within a few weeks or months in a majority of children.
In analogy to the therapy for phenylketonuria, Holt et al first suggested regulating the abnormal blood levels of branchedchain amino acids by means of a completely synthetic diet in which the intake of leucine, isoleucine, valine, and methionine could be carefully
Menkes JH, Solcher H. Maple Syrup Disease: Effects of Dietary Therapy on Cerebral Lipids. Arch Neurol. 1967;16(5):486–491. doi:10.1001/archneur.1967.00470230038004
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