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Tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria

MedGen UID:
Concept ID:
Disease or Syndrome
Synonyms: BH4-responsive HPA/PKU; BH4-responsive hyperphenylalaninemia/phenylketonuria; Tetrahydrobiopterin-responsive HPA/PKU; tetrahydrobiopterin-responsive HPA/PKU; tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
Concept ID:
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
Monarch Initiative: MONDO:0017389
Orphanet: ORPHA293284


A form of phenylketonuria (PKU), an inborn error of amino acid metabolism, characterized by mild to moderate symptoms of PKU including impaired cognitive function, seizures, and behavioral and developmental disorders, and a marked reduction of elevated phenylalanine concentrations after oral loading with tetrahydrobiopterin (BH4), an essential cofactor of phenylalanine hydroxylase. [from ORDO]

Supplemental Content

Table of contents

    Clinical resources

    Practice guidelines


    • ACMG ACT, 2022
      American College of Medical Genetics and Genomics, Newborn Screening ACT Sheet, Elevated Phenylalanine, Phenylalanine hydroxylase deficiency (PAH), 2022
    • ACMG Algorithm, 2022
      American College of Medical Genetics and Genomics, Algorithm, PAH deficiency: Elevated Phenylalanine, 2022

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