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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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Your Question

Can hyperphenylalaninemia caused by tetrahydrobiopterin (BH4) deficiency cause failure to thrive and problems with eating solids in babies?

Our Answer

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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

Can tetrahydrobiopterin (BH4) deficiency cause feeding problems and failure to thrive in babies?

Feeding problems are common in babies with BH4 deficiency and may include poor sucking and/or difficulty swallowing.[3][2]

While failure to thrive is not necessarily a primary feature of BH4 deficiency, it may be a secondary complication. Feeding difficulties can cause failure to thrive.[4] If an affected infant does not feed appropriately, he/she may fail to gain weight and/or grow at the expected rate.
Last updated: 11/2/2012