Dihydropteridine Reductase (DHPR) Deficiency

Dihydropteridine reductase (DHPR) deficiency is an inborn error of tetrahydrobiopterin (BH4) recycling that accounts for approximately one-third of all tetrahydrobiopterin deficiencies. Patients typically exhibit severe neurological symptoms including psychomotor retardation, tonal abnormalities, myoclonic epilepsy, hyperthermia without infections, swallowing difficulties and hypersalivation. Other features include mental retardation and microcephaly. The clinical course of untreated DHPR deficient patients is similar to that in some of the other inborn errors of BH4 metabolism namely 6-pyruvoyl-tetrahydropterin synthase deficiency and GTP cyclohydrolase I deficiency

Tests Available

Forms and Documents

Test Details

  • Confirmation of biochemical diagnosis
  • Carrier testing
  • Prenatal diagnosis in at risk pregnancies


4-5 weeks
2-5 mL Blood - Lavender Top Tube
Buccal Swabs


  • 270.1 Phenylketonuria [PKU], Hyperphenylalaninemia
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  1. Kalkanoglu et al., (2001) Prenat Diagn 21:868-870
  2. Farrugia et al., (2007) Mol Genet Metab 90:277-283
  3. Dianzani et al., (1998) Hum Mutat 12:267-273
  4. Romstad et al., (2000) Hum Genet 107:546-553
  5. Smooker et al., (1999) Hum Mutat 13(6):503-4
  6. BIOMDB: Database of Mutations Causing Tetrahydrobiopterin Deficiencies (database online)