Format

Send to

Choose Destination
See comment in PubMed Commons below
Curr Drug Metab. 2002 Apr;3(2):123-31.

Disorders of tetrahydrobiopterin metabolism and their treatment.

Author information

1
Department of Pediatrics, Osaka City University Graduate School of Medicine, Osaka, Japan. shintakuh@med.osaka-cu.ac.jp

Abstract

Tetrahydrobiopterin (BH4) deficiencies are disorders affecting phenylalanine metabolism in liver and neurotransmitters biosynthesis in brain. BH4 is the essential cofactor in the enzymatic hydroxylation of 3 aromatic amino acids (phenylalanine, tyrosine, and tryptophan). BH4 is synthesized from guanosine triphosphate (GTP) catalyzed by GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydropterin synthase, and sepiapterin reductase (SPR), and in aromatic amino acids hydoxylating system is regenerated by pterin-4a-carbinolamine dehydratase (PCD) and dihydropteridine reductase (DHPR). To date, 4 enzyme deficiencies (GTPCH, PTPS, DHPR, PCD) have been reported and they all follow an autosomal recessive mode of inheritance. The incidence of BH4 deficiency is at 1 in 1,000,000, except that in Taiwanese (much higher than in Japanese and Caucasians). BH4 deficiency has been diagnosed in patients with hyperphenylalaninemia (HPA) by neonatal mass-screening based on BH4 oral loading tests, analysis of urinary or serum pteridines, and measurement of dihydropterindine reductase (DHPR) activity in blood from a Guthrie card. BH4 deficiency without treatment causes combined symptoms of HPA and neurotransmitter (dopamine, norepinephrine, epinephrine, and serotonin) deficiency, such as red hair, psychomotor retardation, and progressive neurological deterioration. Treatment of BH4 deficiencies consists of BH4 supplementation (2-20 mg/kg per day) or diet to control blood phenylalanine concentration and replacement therapy with neurotransmitters precausers (L-dopa/CarbiDOPA and 5-hydroxytryptophan), and supplements of folinic acid in DHPR deficiency.

PMID:
12003346
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Bentham Science Publishers Ltd.
    Loading ...
    Support Center