HYPERPHENYLALANINEMIA DUE TO TETRAHYDROBIOPTERIN DEFICIENCY - A REPORT OF 16 CASES


COSKUN T., OZALP I., TOKATLI A., BLAU N., NIEDERWIESER A.

JOURNAL OF INHERITED METABOLIC DISEASE, vol.16, no.3, pp.605-607, 1993 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 16 Issue: 3
  • Publication Date: 1993
  • Doi Number: 10.1007/bf00711694
  • Journal Name: JOURNAL OF INHERITED METABOLIC DISEASE
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.605-607
  • Hacettepe University Affiliated: Yes

Abstract

Tetrahydrobiopterin (BH4) deficiency accounts for 1-3% of all reported forms of hyperphenylalaninaemia (HPA). Deficiencies of two enzymes, GTP-cyclohydrolase (GTPch; EC 3.5.4.16) and 6-pyruvoyl tetrahydropterin synthase (6-PTS), lead to a defect in BH4 biosynthesis. During the hydroxylation of phenylalanine (Phe) to tyrosine by phenylalanine hydroxylase (PAH; EC 1.14.16.1), BH, is oxidized to quinonoid dihydrobiopterin (qBH2). In order to regenerate BH4, qBH2 is reduced by the enzyme dihydropteridin reductase (DHPR; EC 1.6.99.7). More recently a new form (primapterinuria) due to a possible defect in the activity of dehydratase has been described. Since BH4 is required as cofactor by PAH and by mammalian aromatic amino acid hydroxylases, a deficiency leads not only to HPA but also to a deficiency of biogenic amine neurotransmitters dopamine and serotonin (Blau 1988), its clinical picture and mode of therapy would be expected to be different from the other types of HPA.