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Diagnosis of tetrahydrobiopterin deficiency using filter paper blood spots: further development of the method and 5 years experience

  • Thomas Opladen
  • Bettina Abu Seda
  • Anahita Rassi
  • Beat Thöny
  • Georg F. Hoffmann
  • Nenad Blau
Original Article

Abstract

In every newborn with even mild hyperphenylalaninemia (HPA) tetrahydrobiopterin (BH4) deficiencies need to be excluded as soon as possible. Differential diagnosis is most commonly performed by analysis of urinary neopterin and biopterin. In 2005 a new method for the measurement of neopterin, biopterin and other pterins in dried blood spot (DBS) on filter paper was introduced. In order to evaluate the usefulness of this method as a standard tool for differential diagnosis of HPAs we analyzed neopterin, biopterin, pterin and dihydropteridine reductase activity in DBS from 362 patients with HPA over the period of five years. Age-dependent reference values were established for the HPA population. Sixty-four patients with BH4 deficiency (27 patients with 6-pyruvoyl-tetrahydropterin synthase deficiency, seven with GTP cyclohydrolase I deficiency, and 30 with dihydropteridine reductase) were identified. Reference values for neopterin and biopterin in DBS were calculated for each of the variants. 6-pyruvoyl-tetrahydropterin synthase and GTP cyclohydrolase I deficiency can be diagnosed by neopterin and biopterin analysis alone, while for diagnosis of dihydropteridine reductase deficiency additional determination of enzyme activity from the same DBS is essential. Regarding test sensitivity, the interpretation of neopterin and biopterin concentration per hemoglobin is more valid than the interpretation of neopterin and biopterin per liter. Percentage of biopterin, of the sum of neopterin and biopterin should always be calculated. In addition, determination of hemoglobin concentration is essential as a measure for efficient extraction of neopterin and biopterin. Although the measurement of neopterin and biopterin in urine is more sensitive due to the higher concentrations present, our data prove the usefulness of their measurement from DBS for the routine diagnosis of BH4 deficiencies.

Keywords

Newborn Screening Neopterin Pterin Biopterin Dihydropteridine Reductase 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations

BH4

Tetrahydrobiopterin

DBS

Dried blood spot

DHPR

Dihydropteridine reductase

GTPCH

GTP cyclohydrolase I

HPA

Hyperphenylalaninemia

PCD

Pterin-4a-carbinolamine dehydratase

PKU

Phenylketonuria

PTPS

6-pyruvoyl-tetrahydropterin synthase

Notes

Acknowledgements

This work was supported by the Swiss National Science Foundation (to N.B. and B.T.) grant no. 31003A-119982.

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Copyright information

© SSIEM and Springer 2011

Authors and Affiliations

  • Thomas Opladen
    • 1
  • Bettina Abu Seda
    • 2
  • Anahita Rassi
    • 2
  • Beat Thöny
    • 2
    • 3
    • 4
  • Georg F. Hoffmann
    • 1
  • Nenad Blau
    • 2
    • 3
    • 4
  1. 1.Division of Inborn Metabolic DiseasesUniversity Children’s Hospital HeidelbergHeidelbergGermany
  2. 2.Division of Clinical Chemistry and BiochemistryUniversity Children’s Hospital ZürichZürichSwitzerland
  3. 3.Zürich Center for Integrative Human Physiology (ZIHP)ZürichSwitzerland
  4. 4.Research Center for Children (RCC)ZürichSwitzerland

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