hyperphenylalaninemia due to tetrahydrobiopterin deficiency
Findings
No curated finding names hyperphenylalaninemia due to tetrahydrobiopterin deficiency yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
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) 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.
Definition from the Mondo Disease Ontology (MONDO:0016543), read 2026-09-29. CC BY 4.0.
Features
24 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- HyperphenylalaninemiaHPOHP:0004923
- Very frequent (80% to 99% of cases)
- Abnormal circulating biopterin concentrationHPOHP:0040210
- Frequent (30% to 79% of cases)
- Abnormal circulating neopterin concentrationHPOHP:0040206
- Frequent (30% to 79% of cases)
- Abnormal urinary nitrogen compound levelHPOHP:0040416
- Frequent (30% to 79% of cases)
- Atypical behaviorHPOHP:0000708
- Frequent (30% to 79% of cases)
- Decreased CSF homovanillic acid concentrationHPOHP:0003785
- Frequent (30% to 79% of cases)
Show the remaining 12
- Delayed speech and language developmentHPOHP:0000750
- Occasional (5% to 29% of cases)
- DystoniaHPOHP:0001332
- Occasional (5% to 29% of cases)
- Elevated urinary 7-biopterin levelHPOHP:0033594
- Occasional (5% to 29% of cases)
- HypertoniaHPOHP:0001276
- Occasional (5% to 29% of cases)
- HypomagnesemiaHPOHP:0002917
- Occasional (5% to 29% of cases)
- Maturity-onset diabetes of the youngHPOHP:0004904
- Occasional (5% to 29% of cases)
Where it sits
Other names
2 names
Resolves to: hyperphenylalaninemia due to tetrahydrobiopterin deficiency
- Also called
- hyperphenylalaninemia due to BH4 deficiencynon-phenylketonuric hyperphenylalaninemia