title: Single-step mutation scanning of the 6-pyruvoyltetrahydropterin synthase gene in patients with hyperphenylalaninemia.
abstract: BACKGROUND
  Deficiency of 6-pyruvoyltetrahydropterin synthase (PTPS) is a recessively inherited disorder that leads to depletion of 5,6,7, 8-tetrahydrobiopterin, the obligatory cofactor for hydroxylation of phenylalanine, tyrosine, and tryptophan. A marker for neonatal detection of PTPS deficiency is hyperphenylalaninemia (HPA). Molecular analysis would provide a simple and reliable means for distinguishing PTPS deficiency from other potential causes of HPA.
  
  
  METHODS
  We developed a method based on PCR in combination with denaturing gradient gel electrophoresis (DGGE) that rapidly scans the six coding sequences and all splice sites of the PTPS gene (PTS) for mutations. This method was used to examine the status of the PTS gene in control samples with known PTS mutations and in five patients with PTPS deficiency.
  
  
  RESULTS
  Two features of the PTS gene posed particular problems in relation to DGGE analysis: the very high GC content of exon 1, and a 15-bp poly(dT) stretch in the acceptor splice site of intron 1. Both problems were solved by special design of amplification primers. PCR and DGGE conditions were adjusted to allow simultaneous analysis of all six regions of the PTS gene. Using this one-step approach, all control mutations were readily resolved. Among the five PTPS patients, four mutations were identified, including IVS1-3C-->G, IVS2-7T-->A, V57del, and V97M (289G-->A). The IVS1-3C-->G mutation was shown by reverse transcription-PCR analysis to produce multiple splice variants.
  
  
  CONCLUSIONS
  We have established a fast and reliable screening method for detection of mutations and small deletions/insertions in the PTS gene. This method should be useful for rapid diagnosis of PTPS deficiency in newborns with HPA.
authors.affiliation: The John F. Kennedy Institute, Gl. Landevej 7, 2600 Glostrup, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Romstad
authors.forename: P
authors.initials: P
authors.lastname: Guldberg
authors.forename: N
authors.initials: N
authors.lastname: Blau
authors.forename: F
authors.initials: F
authors.lastname: Güttler
mesh_terms: D000483:Alleles; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005091:Exons; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D009154:Mutation; D010641:Phenotype; D010661:Phenylketonurias / Q000175:diagnosis / Q000201:enzymology / Q000235:genetics*; D019761:Phosphorus-Oxygen Lyases / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D013696:Temperature
chemical_list: D019761:Phosphorus-Oxygen Lyases; C043497:6-pyruvoyltetrahydropterin synthase