Hyperphenylalaninemia due to dihydropteridine reductase deficiency. Assay of the enzyme in fibroblasts from affected infants, heterozygotes, and in normal amniotic fluid cells

Sheldon Milstien, Neil A. Holtzman, Margaret E. O'Flynn, George H. Thomas, Ian J. Butler, Seymour Kaufman

Research output: Contribution to journalArticlepeer-review

Abstract

Two infant siblings with modest elevations of serum phenylalanine concentrations had seizures and developmental regression; they died in their second year. Dihydropteridine reductase activity, which can be measured in normal cultured skin fibroblasts, was measured in the younger sibling and was absent. Parent of the two siblings and parents of a previously reported patient all showed 50% or less of the normal dihydropteridine reductase activity in their cultured fibroblasts. Dihydropteridine reductase activity is also present in normal cultured amniotic fluid cells, offering the possibility of prenatal diagnosis. Absence of dihydropteridine reductase results not only in a defect in the conversion of phenylalanine to tyrosine, but also in the biosynthesis of the neurotransmitters, dopamine, norepinephrine, and serotonin. Since deficiencies in these neurotransmitters would not be alleviated by a phenylalanine-restricted diet, it is important to establish the nature of the enzymatic defect in all suspected variants of phenylketonuria.

Original languageEnglish (US)
Pages (from-to)763-766
Number of pages4
JournalThe Journal of pediatrics
Volume89
Issue number5
DOIs
StatePublished - Nov 1976

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

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