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

Tyrosinemia type 2


Other Names:
Tyrosinemia type II; Richner Hanhart syndrome; TAT deficiency; Tyrosinemia type II; Richner Hanhart syndrome; TAT deficiency; Tyrosine transaminase deficiency; Keratosis palmoplantaris with corneal dystrophy; Oregon type tyrosinemia; Tyrosinosis oculocutaneous type; Tyrosine aminotransferase deficiency; Oculocutaneous tyrosinemia See More
Categories:
Tyrosinemia type 2 is a genetic disorder in which individuals have elevated blood levels of the amino acid tyrosine, a building block of most proteins. This condition can affect the eyes, skin, and intellectual development. Symptoms of tyrosinemia type 2 often begin in early childhood and include excessive tearing, abnormal sensitivity to light (photophobia), eye pain and redness, and painful skin lesions on the palms and soles (palmoplantar hyperkeratosis). About 50 percent of individuals with this condition have an intellectual disability. Tyrosinemia type 2 is caused by a deficiency of the enzyme tyrosine aminotransferase, one of the enzymes required for the multi-step process that breaks down tyrosine. This enzyme shortage is caused by mutations in the TAT gene. This condition is inherited in an autosomal recessive manner.[1] There is no cure for this condition; however, some of the symptoms may be managed with a diet that limits certain amino acids, such as phenylalanine and tyrosine.[2] A medication called NTBC may also be used to help control the amount of tyrosine in the body.[3]
Last updated: 5/24/2017

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
80%-99% of people have these symptoms
Corneal opacity 0007957
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Palmoplantar keratoderma
Thickening of palms and soles
0000982
30%-79% of people have these symptoms
Abnormality of amino acid metabolism 0004337
Hyperhidrosis
Excessive sweating
Increased sweating
Profuse sweating
Sweating
Sweating profusely
Sweating, increased
[ more ] 		0000975
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Photophobia
Extreme sensitivity of the eyes to light
Light hypersensitivity
[ more ] 		0000613
5%-29% of people have these symptoms
Abnormality of the nail 0001597
Ataxia 0001251
Malar flattening
Zygomatic flattening
0000272
Microcephaly
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference
[ more ] 		0000252
Neurological speech impairment
Speech disorder
Speech impairment
Speech impediment
[ more ] 		0002167
Seizure 0001250
Tremor 0001337
Visual loss
Loss of vision
Vision loss
[ more ] 		0000572
Percent of people who have these symptoms is not available through HPO
4-Hydroxyphenylpyruvic aciduria 0003161
Abnormality of the skin 0000951
Autosomal recessive inheritance 0000007
Growth delay
Delayed growth
Growth deficiency
Growth failure
Growth retardation
Poor growth
Retarded growth
[ more ] 		0001510
Herpetiform corneal ulceration 0007812
Hypertyrosinemia
Increased tyrosine in blood
0003231
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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

  • An ACTion (ACT) sheet is available for this condition that describes the short-term actions a health professional should follow when an infant has a positive newborn screening result. ACT sheets were developed by experts in collaboration with the American College of Medical Genetics.
  • An Algorithm flowchart is available for this condition for determining the final diagnosis in an infant with a positive newborn screening result. Algorithms are developed by experts in collaboration with the American College of Medical Genetics.
  • Baby's First Test is the nation's newborn screening education center for families and providers. This site provides information and resources about screening at the local, state, and national levels and serves as the Clearinghouse for newborn screening information.
  • National Newborn Screening and Global Resource Center (NNSGRC) provides information and resources in the area of newborn screening and genetics to benefit health professionals, the public health community, consumers and government officials.
The management of tyrosinemia type 2 revolves around dietary restriction of phenylalanine and tyrosine. This controlled diet typically lowers the blood levels of tyrosine, resulting in rapid resolution of the skin and eye symptoms. However, the effects of this controlled diet on central nervous system involvement (mental development) remains unclear. In some cases, skin lesions may be treated with oral retinoids.[2]
Last updated: 7/25/2012

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

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
As the ocular findings are often the initial manifestations of the disease, the pseudodendritic keratitis is often mistaken for herpes simplex keratitis (see this term).
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Patient Registry

  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Tyrosinemia type 2. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

    Registries for Tyrosinemia type 2:
    NBS Connect
     

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

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

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
  • 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 Tyrosinemia type 2. 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. Submit a new question

  • How might tyrosinemia type 2 be treated? See answer


  1. Tyrosinemia. Genetics Home Reference (GHR). August 2015; https://ghr.nlm.nih.gov/condition/tyrosinemia.
  2. Wendel U. Tyrosinemia type 2. Orphanet. November 2010; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=28378.
  3. Tyrosinemia, Type II. baby's first test. http://www.babysfirsttest.org/newborn-screening/conditions/tyrosinemia-type-ii. Accessed 5/24/2017.