Search for a rare disease
Other search option(s)
Mild hyperphenylalaninemia (HPA) is a rare form of phenylketonuria (see this term), an inborn error of amino acid metabolism, characterized by mild symptoms of HPA.
ORPHA:79651Classification level: Subtype of disorder
- Mild HPA
- Non-PKU HPA
- Prevalence: Unknown
- Inheritance: Autosomal recessive
- Age of onset: Infancy, Neonatal
- ICD-10: E70.1
- OMIM: -
- UMLS: -
- MeSH: -
- GARD: -
- MedDRA: -
Prevalence is unknown but the condition is thought to be rare worldwide. A particularly high prevalence of mild HPA has been reported in Spain.
Patients with blood phenylalanine (Phe) concentrations of 120-600 micromol/L before initiation of treatment are considered to have mild HPA. Clinical signs include impaired cognitive function, and behavioral and developmental disorders.
The condition appears to be caused by certain mutations in the PAH gene (12q22-q24.2) resulting in at least 5% residual phenylalanine hydroxylase enzyme activity, which leads to the slightly raised Phe blood concentrations characteristic of mild HPA. The disorder is transmitted in an autosomal recessive manner.
Management and treatment
The decision on whether to treat should be based on Phe levels, but treatment is important in pregnant women due to the teratogenic potential of elevated maternal Phe.