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Disease Profile

Tyrosinemia type 2

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

<1 / 1 000 000

US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Tyrosinemia type II; Richner Hanhart syndrome; TAT deficiency;


Congenital and Genetic Diseases; Eye diseases; Metabolic disorders;


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]


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.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Corneal opacity
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific

[ more ]

Palmoplantar keratoderma
Thickening of palms and soles
30%-79% of people have these symptoms
Abnormality of amino acid metabolism
Excessive sweating
Increased sweating
Profuse sweating
Sweating profusely
Sweating, increased

[ more ]

Involuntary, rapid, rhythmic eye movements
Extreme sensitivity of the eyes to light
Light hypersensitivity

[ more ]

5%-29% of people have these symptoms
Abnormality of the nail
Malar flattening
Zygomatic flattening
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

Neurological speech impairment
Speech disorder
Speech impairment
Speech impediment

[ more ]

Visual loss
Loss of vision
Vision loss

[ more ]

Percent of people who have these symptoms is not available through HPO
4-Hydroxyphenylpyruvic aciduria
Abnormality of the skin
Autosomal recessive inheritance
Growth delay
Delayed growth
Growth deficiency
Growth failure
Growth retardation
Poor growth
Retarded growth

[ more ]

Herpetiform corneal ulceration
Increased tyrosine in blood


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]


      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

        Learn more

        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.


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

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