Synonyms: BH4-responsive HPA/PKU | BH4-responsive hyperphenylalaninemia/phenylketonuria | Tetrahydrobiopterin-responsive HPA/PKU
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.
Data from Orphanet are used to provide information on a disease's name, synonym(s), and overview. Reference: Access aggregated data from Orphanet at Orphadata. Orphadata: Free access data from Orphanet. © INSERM 1999. Available on http://www.orphadata.org. Data version May 2026
Newly diagnosed with
Tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria?
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Advocacy Organizations
Access to Life NGO
Our mission is to improve the lives of people affected by genetic epilepsies by empowering patients and families, advancing access to diagnosis and treatment, supporting research, and advocating for equitable, patient-centered care in Ukraine in alignment with global rare disease standards.
Canadian PKU and Allied Disorders (CanPKU)
“To improve the lives of people living with PKU and other inherited metabolic disorders by supporting education, advocacy, access to care, and community connection.”
FamilieSCN2A Foundation
Our MISSION is to accelerate research, build community and advocate to improve the lives of those affected by SCN2A-related disorders around the world.
Genetic Epilepsy Team Australia
Collaboration of research and care
Intermountain PKU and Allied Disorders. Association
The Intermountain PKU and Allied Disorders Association is dedicated to providing support and services to individuals and families with PKU and allied disorders. Our mission is to provide education and resources to individuals and families, to encourage research, and to increase public awareness of these rare conditions.
Louisiana Metabolic Disorders Coalition
We support, educate, and advocate for patients & families affected by metabolic disorders.
Mississippi Metabolics Foundation
Our mission at Mississippi Metabolics Foundation (MMF) is to advocate, educate, and support families in MS affected by genetic metabolic disorders/inborn errors of metabolism (IEM's). MMF promotes initiatives and further advancements in legislation, education, research, clinical trials, studies, therapies, targeted treatments, and eventual cures for IEM’s and all rare diseases.
National PKU Alliance
Our mission is to improve the lives of individuals with PKU, pursue a cure by expanding research and provide education and support to individuals living with PKU and their caregivers.
PO”UAP PKU “Special children”
Help for patients and families with phenylketonuria
Rare Epilepsy Network (REN)
Improving outcomes of people with rare epilepsies through an innovative collaborative infrastructure that drives urgent, patient-centered research, educaiton and advocacy.
Uganda Alliance of Patients Organization
Supporting patients to access quality, safe and patient-centered healthcare services.
flok Health (formerly National PKU News)
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Clinical Trials
For a list of clinical trials in this disease area, please click here.