Overview
A disorder of histidine metabolism is a rare inherited condition where the body cannot properly break down an amino acid called histidine. The most well-known form is called histidinemia (also spelled histidinaemia), caused by a shortage of an enzyme called histidase (or histidine ammonia-lyase). When this enzyme does not work properly, histidine builds up in the blood, urine, and sometimes the brain. For many years, histidinemia was thought to cause serious problems like intellectual disability and speech delays. However, large-scale newborn screening studies — especially in Japan and North America — have shown that most people with histidinemia have no symptoms at all and live completely normal lives. A small number of affected individuals may experience speech and language delays or mild learning difficulties, but it is now believed these may not always be directly caused by the enzyme deficiency itself. There is no specific drug treatment needed for most people. The condition is usually detected through routine newborn blood screening. Ongoing follow-up with a metabolic specialist is recommended, especially in childhood, to monitor development and provide support if needed.
Key symptoms:
Elevated histidine levels in the blood (usually found on newborn screening)High levels of histidine in the urineSpeech and language delays (in a minority of cases)Mild learning difficulties (in some individuals)Behavioral differences such as attention problems (reported in some cases)Most affected people have no symptoms at all
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Disorder of histidine metabolism.
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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 histidine metabolism.
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Caregiver Resources
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Questions for your doctor
Bring these to your next appointment
- Q1.Does my child actually need any treatment, or is monitoring enough?,Should we make any changes to my child's diet, or is a normal diet fine?,What developmental milestones should I watch closely, and when should I be concerned?,How often do we need follow-up appointments, and what tests will be done?,What is the chance that future children will also have this condition?,Should other family members be tested for this condition?,Are there any long-term health risks I should know about as my child grows into adulthood?
Common questions about Disorder of histidine metabolism
What is Disorder of histidine metabolism?
A disorder of histidine metabolism is a rare inherited condition where the body cannot properly break down an amino acid called histidine. The most well-known form is called histidinemia (also spelled histidinaemia), caused by a shortage of an enzyme called histidase (or histidine ammonia-lyase). When this enzyme does not work properly, histidine builds up in the blood, urine, and sometimes the brain. For many years, histidinemia was thought to cause serious problems like intellectual disability and speech delays. However, large-scale newborn screening studies — especially in Japan and North A
How is Disorder of histidine metabolism inherited?
Disorder of histidine metabolism follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Disorder of histidine metabolism typically begin?
Typical onset of Disorder of histidine metabolism is neonatal. Age of onset can vary across affected individuals.
Which specialists treat Disorder of histidine metabolism?
3 specialists and care centers treating Disorder of histidine metabolism are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.