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June 1964

5-Hydroxytryptophan Administration in Phenylketonuria

Author Affiliations

Thomas L. Perry, MD, Department of Pharmacology, The University of British Columbia, Vancouver 8, BC, Canada.; From the Department of Pharmacology, University of British Columbia, Vancouver, Canada and The Woodlands School, New Westminster, Canada.

Am J Dis Child. 1964;107(6):586-589. doi:10.1001/archpedi.1964.02080060588006

Introduction  In phenylketonuria an enzymatic defect in the liver results in a failure of conversion of phenylalanine to tyrosine. The alternative metabolic pathways followed by the accumulating phenylalanine have been clarified. However, the exact mechanism by which the metabolic error in turn produces mental deficiency in untreated phenylketonurics has not been established. One possible explanation for the mental deficiency was advanced in 1957 by Paré et al1 who first noted a defect in the 5-hydroxyindole pathway of tryptophan metabolism in phenylketonurics. The presence of serotonin in brain, and the mental abnormalities produced by some serotonin antagonists, have suggested a possible role for this amine in mental function. Paré et al1 suggested that a failure in serotonin production might play some part in the pathogenesis of the mental defect in phenylketonuria.Since then it has been demonstrated2-4 that rats rendered artificially phenylketonuric by the administration of large amounts