Evaluation of a fetus at risk for dihydropteridine reductase deficiency bydirect mutation analysis using denaturing gradient gel electrophoresis

Dihydropteridine reductase (DHPR) is an enzyme involved in the recycling of tetrahydrobiopterin (BH4), which is an obligate co-factor of the aromatic amino acid hydroxylases. DHPR deficiency is a rare, autosomal recessive dis order caused by mutations in the QDPR gene. DHPR-deficient patients are dia gnosed by a lack of response to a low phenylalanine diet and by severe neur ological symptoms. Final diagnosis is made by measurements of neurotransmit ters and pterin metabolites in cerebrospinal fluid (CSF) and urine, in addi tion to DHPR enzyme activity, which can be assessed in whole red blood cell s. Treatment of DHPR deficiency can be difficult and the outcome is not alw ays satisfying, even if all treatment strategies are followed. Therefore pr enatal diagnosis is of great importance in affected families. Prenatal diag nosis is possible by measuring DHPR activity in different cell types but th is is time consuming. More than 25 different mutations have to date been id entified in the QDPR gene and direct identification of a mutation in a fetu s would be easy and rapid. We have developed a method based on denaturing g radient gel electrophoresis (DGGE) for the analysis of the QDPR gene. The m ethod is useful for rapid and simultaneous scanning of all exons and flanki ng intronic sequences of the QDPR gene. We describe the first prenatal diag nosis conducted using this method. Copyright (C) 2001 John Wiley & Sons, Lt d.