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Synonym(s) Hyperphenylalaninemia due to BH4 deficiency
Hyperphenylalaninemia due to tetrahydrobiopterin deficiency
Non-phenylketonuric hyperphenylalaninemia
Prevalence 1-9 / 1 000 000
Inheritance Autosomal recessive
Age of onset Neonatal
  • E70.1
  • C0751436
MeSH -
MedDRA -


Disease definition

Hyperphenylalaninemia (HPA) due to tetrahydrobiopterin (BH4) deficiency, also known as malignant HPA is an amino acid disorder with neonatal onset that is clinically characterized by the classic manifestations of phenylketonuria (PKA; see this term) and that later on is clinically differentiated by neurologic symptoms such as microcephaly, intellectual disability, central hypotonia, delayed motor development, peripheral spasticity and seizures, that develop and persist despite an established metabolic control of plasma phenylalanine.

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