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Genetic and Rare Diseases Information Center (GARD)

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Tetrahydrobiopterin deficiency

Other Names for this Disease
  • BH4 deficiency
  • Hyperphenylalaninemia caused by a defect in biopterin metabolism
  • Hyperphenylalaninemia, non-phenylketonuric
  • Non-phenylketonuric hyperphenylalaninemia
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What are the signs and symptoms of tetrahydrobiopterin deficiency?

Infants with tetrahydrobiopterin (BH4) deficiency typically appear normal and healthy at birth.[1][2] Neurological signs and symptoms usually become apparent over time, and can range from mild to severe.[3][2] These may include abnormal muscle tone; poor sucking and coordination; seizures; and delayed motor development.[1] Other manifestations may include decreased spontaneous movements and difficulty swallowing.[3][2]

Without early and appropriate treatment, signs and symptoms progress and affected individuals may experience irreversible intellectual disability, behavioral problems, an inability to control body temperature, and even death in severe cases.[3][1]
Last updated: 11/2/2012

  1. Tetrahydrobiopterin Deficiency. NORD. May 23, 2008; Accessed 10/31/2012.
  2. Noah S Scheinfeld. Tetrahydrobiopterin Deficiency. Medscape Reference. June 27, 2012; Accessed 11/2/2012.
  3. Tetrahydrobiopterin deficiency. Genetics Home Reference. July 2011; Accessed 11/2/2012.