Contract grant sponsor: Swiss National Science Foundation (31003A-119982).
Tetrahydrobiopterin, its Mode of Action on Phenylalanine Hydroxylase, and Importance of Genotypes for Pharmacological Therapy of Phenylketonuria
Article first published online: 1 MAY 2013
© 2013 WILEY PERIODICALS, INC.
Volume 34, Issue 7, pages 927–936, July 2013
How to Cite
Heintz, C., Cotton, R. G.H. and Blau, N. (2013), Tetrahydrobiopterin, its Mode of Action on Phenylalanine Hydroxylase, and Importance of Genotypes for Pharmacological Therapy of Phenylketonuria. Hum. Mutat., 34: 927–936. doi: 10.1002/humu.22320
Communicated by Johannes Zschocke
- Issue published online: 18 JUN 2013
- Article first published online: 1 MAY 2013
- Accepted manuscript online: 4 APR 2013 09:30PM EST
- Manuscript Revised: 20 MAR 2013
- Manuscript Accepted: 20 MAR 2013
- Manuscript Received: 12 NOV 2012
- Swiss National Science Foundation. Grant Number: 31003A-119982
In about 20%–30% of phenylketonuria (PKU) patients (all phenotypes of PAH deficiency), Phe levels may be controlled through phenylalanine hydroxylase cofactor tetrahydrobiopterin therapy. These patients can be diagnosed by an oral tetrahydrobiopterin challenge and are characterized by mutations coding for proteins with substantial residual PAH activity. They can be treated with a commercially available synthetic form of tetrahydrobiopterin, either as a monotherapy or as adjunct to the diet. This review article summarizes molecular and metabolic bases of PKU and the importance of the tetrahydrobiopterin loading test used for PKU patients. On the basis of in vitro residual PAH activity, more than 1,200 genotypes from patients challenged with tetrahydrobiopterin were categorized as predictive for tetrahydrobiopterin responsiveness or non-responsiveness and correlated with the loading test, phenotype, and residual in vitro PAH activity. The coexpression of two distinct PAH mutant alleles revealed possible dominance effects (positive or negative) by one of the mutations on residual activity as result of interallelic complementation. The treatment of the transfected cells with tetrahydrobiopterin showed an increase in residual PAH activity with several mutations coexpressed.