Overview
Disorders of phenylalanine or tyrosine metabolism are a group of inherited conditions where the body cannot properly break down two amino acids — phenylalanine and tyrosine — that come from the protein we eat. These amino acids are building blocks the body normally processes through a series of chemical steps. When one of those steps is blocked due to a missing or faulty enzyme, harmful substances can build up, or important products the body needs may not be made in enough quantity. The most well-known condition in this group is phenylketonuria (PKU), where phenylalanine builds up and can damage the brain if not treated early. Other conditions include tyrosinemia (types I, II, and III), alkaptonuria, and disorders affecting the production of melanin or thyroid hormones. Symptoms vary widely depending on which specific disorder is present, but can include intellectual disability, liver disease, skin and eye problems, and joint pain. Treatment depends on the specific disorder but often includes a carefully managed low-protein diet, special medical formulas, and in some cases, medications. Many of these conditions are detected through newborn screening programs, which allows treatment to begin early and greatly improves outcomes. With proper management, many people with these disorders can live healthy, fulfilling lives.
Key symptoms:
Intellectual disability or learning difficultiesDelayed development in infants and young childrenLiver damage or liver failureYellowing of the skin or eyes (jaundice)Skin rashes or sensitivity to lightEye irritation or corneal damageJoint pain and stiffnessDark urine or urine with an unusual smellSeizuresBehavioral problems or mood changesPoor growth or failure to thrive in infantsMusty or unusual body odorKidney problems
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Variable
Can begin at different ages, from infancy through adulthood
Treatments
No FDA-approved treatments are currently listed for Disorder of phenylalanin or tyrosine metabolism.
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Specialists
View all specialists →No specialists are currently listed for Disorder of phenylalanin or tyrosine metabolism.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Disorder of phenylalanin or tyrosine metabolism.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
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Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Which specific disorder of phenylalanine or tyrosine metabolism does my child or I have, and what does that mean for us?,What dietary changes are needed, and can we work with a metabolic dietitian?,Are there medications approved for my specific condition, and would I or my child benefit from them?,How often do we need blood tests and specialist check-ups?,What are the warning signs of a metabolic crisis, and what should I do if one happens?,Are there clinical trials or new treatments I should know about?,What support is available for managing the emotional and social challenges of this condition?
Common questions about Disorder of phenylalanin or tyrosine metabolism
What is Disorder of phenylalanin or tyrosine metabolism?
Disorders of phenylalanine or tyrosine metabolism are a group of inherited conditions where the body cannot properly break down two amino acids — phenylalanine and tyrosine — that come from the protein we eat. These amino acids are building blocks the body normally processes through a series of chemical steps. When one of those steps is blocked due to a missing or faulty enzyme, harmful substances can build up, or important products the body needs may not be made in enough quantity. The most well-known condition in this group is phenylketonuria (PKU), where phenylalanine builds up and can dam
How is Disorder of phenylalanin or tyrosine metabolism inherited?
Disorder of phenylalanin or tyrosine metabolism follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.