National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Histidinemia


Other Names:
Histidase deficiency; HIS deficiency; HAL deficiency; Histidase deficiency; HIS deficiency; HAL deficiency; Histidine ammonia-lyase deficiency See More
Categories:
Histidinemia is an inherited metabolic condition characterized by elevated levels of the amino acid histidine in blood, urine, and cerebrospinal fluid. In most cases, people with this condition have no health problems and may not even know that they are affected. Individuals with histidinemia who also experience a medical complication during or shortly after birth (such as a temporary lack of oxygen), may be at an increased risk of developing intellectual disability, behavioral problems, or learning disabilities.[1][2][3]

Histidinemia is caused by changes (mutations) in the HAL gene. This gene provides instructions for making an enzyme called histidase, which breaks down histidine into a molecule called urocanic acid. If histidase doesn't do its job properly, histidine levels become elevated.[1] Histidinemia is inherited in an autosomal recessive pattern.[1][2][3] Because there are no symptoms associated with this condition, treatment is not necessary.[2][3]
Last updated: 11/14/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
100% of people have these symptoms
Histidinuria
High urine histidine levels
0002927
Hyperhistidinemia
High blood histidine level
0010906
5%-29% of people have these symptoms
Behavioral abnormality
Behavioral changes
Behavioral disturbances
Behavioral disorders
Psychiatric disturbances
Psychiatric disorders
Behavioural/Psychiatric abnormality
Behavioral/psychiatric abnormalities
Behavioral problems
[ more ] 		0000708
Neurological speech impairment
Speech impairment
Speech disorder
Speech impediment
[ more ] 		0002167
1%-4% of people have these symptoms
Hyperactivity
More active than typical
0000752
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Moderate global developmental delay 0011343
Specific learning disability 0001328
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance 0000006
Autosomal recessive inheritance 0000007
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Last updated: 7/1/2020

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Newborn Screening

  • The Newborn Screening Coding and Terminology Guide has information on the standard codes used for newborn screening tests. Using these standards helps compare data across different laboratories. This resource was created by the National Library of Medicine.

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Histidinemia. This website is maintained by the National Library of Medicine.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Histidinemia. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Histidinemia. Genetics Home Reference (GHR). August 2009; https://ghr.nlm.nih.gov/condition/histidinemia.
  2. Levy HL. Histidinemia. National Organization for Rare Disorders (NORD). 2015; http://rarediseases.org/rare-diseases/histidinemia/.
  3. Brosco J. Histidinemia. Orphanet. January 2015; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=2157.