Synonyms: Hyperphenylalaninemia due to BH4 deficiency | Non-phenylketonuric hyperphenylalaninemia
An amino acid disorder with neonatal onset that is clinically characterized by the classic manifestations of phenylketonuria (PKA) 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.
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 July 2026
Newly diagnosed with
Hyperphenylalaninemia due to tetrahydrobiopterin deficiency?
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Advocacy Organizations
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.”
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.
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.