Disease Directory Phenylketonuria
Metabolic

Phenylketonuria

Also known as: PKU, PAH deficiency, phenylalanine hydroxylase deficiency, hyperphenylalaninemia

Prevalence

1-5 per 10,000 (Orphanet)

Onset

Neonatal

Type

Autosomal recessive genetic

Gene

PAH

About Phenylketonuria

Phenylketonuria (PKU) is an inborn error of metabolism caused by mutations in the PAH gene encoding phenylalanine hydroxylase, the enzyme that converts phenylalanine to tyrosine. Without treatment, elevated blood phenylalanine causes progressive intellectual disability and neurological damage. PKU is detected by newborn screening, and lifelong management includes a low-phenylalanine diet; sapropterin (Kuvan) and pegvaliase (Palynziq) are approved pharmacological therapies.

Common Clinical Features

Intellectual disability (untreated) Seizures Behavioral problems Eczema Musty body odor Hypopigmentation Anxiety and depression

Clinical Trial Eligibility Tips

What to know before applying to Phenylketonuria trials.

Sapropterin (BH4) responsiveness testing is required before enrollment in BH4-related trials — responders and non-responders are separate cohorts

Blood phenylalanine levels at baseline and throughout diet history are key eligibility and outcome measures

Pegvaliase (Palynziq) trials typically require documented failure or intolerance of dietary management

Maternal PKU trials specifically target women of childbearing age — pregnancy planning is a distinct eligibility pathway

Patient Resources

Patient Organization

National PKU Alliance

Visit website ↗

Natural History Registry

PKU Registry

Join registry ↗

Orphanet

European reference resource for rare diseases (ORPHA:716)

View on Orphanet ↗

NORD

National Organization for Rare Disorders

Search NORD ↗

Find recruiting Phenylketonuria trials

Search 500,000+ studies from ClinicalTrials.gov, filtered for Phenylketonuria. Updated daily.

Related Rare Diseases