Tyrosinemia Type 1

Other Names

Fumarylacetoacetase deficiency

Fumarylacetoacetate hydrolase deficiency (FAH deficiency)

Hereditary infantile tyrosinemia

Hepatorenal tyrosinemia

Hereditary tyrosinemia type 1 (HT1)

Diagnosis Coding

E70.21, Tyrosinemia

Disorder Category

An amino acidemia



Elevated tyrosine; elevated succinylacetone

Tested By

Tandem mass spectrometry (MS/MS); sensitivity~80% (with tyrosine), >99% with succinylacetone; specificity=99.98% [Schulze: 2003]


Tyrosinemia type I is caused by a deficiency of fumarylacetoacetase (FAH), one of the last enzymes in aromatic amino acid metabolism. This results in a mild increase in plasma tyrosine (that can be missed by newborn screening) and the accumulation of succinylacetone (that is specific for this condition) and related compounds that are extremely toxic. These compounds are produced in the liver and kidney resulting in liver failure, cirrhosis, and development of liver cancer. Patients can also present with failure to thrive and rickets due to severe renal tubular dysfunction.


About 1:125,000 live births [Schulze: 2003]


Autosomal recessive

Prenatal Testing

DNA testing, biochemical testing (succinylacetone) by amniocentesis

Clinical Characteristics

With treatment, a >90% survival rate can be expected, along with normal growth, normalization of liver function and prevention of cirrhosis, correction of renal tubular acidosis, and resolution of secondary rickets. Early treatment is associated with reduced incidence of hepatic cancer. Treatment consists of a diet low in tyrosine and phenylalanine and use of a drug (nitisone or NTBC) that prevents formation of succinylacetone, the toxic agent responsible for liver and kidney damage. Patients with evidence of cirrhosis or liver cancer require liver transplantation. Without treatment, chronic problems ensue, including liver disease leading to cirrhosis and hepatocellular carcinoma, renal tubular disease (Fanconi syndrome), rickets, failure to thrive, and coagulation disorders. Repeated neurologic crises may occur involving mental status change, abdominal pain, peripheral neuropathy, and/or respiratory failure. These are due to the accumulation of delta amino levulinic acid, whose metabolism inhibited by succinylacetone. Death usually occurs by 10 years of age.

Initial symptoms may include:
  • Severe liver involvement in the young infant with:
    • Jaundice
    • Ascites
    • Loss of clotting factor synthesis
    • GI bleeding
  • Or development later in the first year of life:
    • Liver dysfunction
    • Renal involvement
    • Growth failure
    • Rickets
    • "Boiled cabbage" or "rotten mushroom" odor to the body and urine
Treatment consists of a diet low in tyrosine and phenylalanine and therapy with the orphan drug NTBC (aka nitisinone) that inhibits an enzyme (p—OH-phenylpyruvic acid dioxygenase) in the degradative pathway of tyrosine. Inhibition of this enzyme causes the immediate disappearance of succinylacetone. Renal Fanconi syndrome and rickets require treatment with activated vitamin D followed by standard vitamin D supplementation. Patients need repeated monitoring for the appearance of liver cancer with ultrasounds (MRI in suspicious cases) and alpha-fetoprotein levels.

Follow-up Testing after Positive Screen

Quantitative plasma amino acid analysis, urine organic acid analysis. DNA testing needs to be obtained for definitive diagnostic confirmation.

Primary Care Management

Upon Notification of the + Screen

If the Diagnosis is Confirmed

  • Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill (see Tyrosinemia Type 1 - Information for Parents (STAR-G)).
  • Support initiation and maintenance of dietary restriction of phenylalanine and tyrosine.
  • Treatment with Nitisinone [NTBC or 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3-cyclohexanedione)], a competitive inhibitor of an upstream enzyme that reduces the production of toxic metabolites.
  • Vitamin D supplements may be indicated for affected children.
  • Regular blood and urine tests to monitor amino acid, succinylacetone, and alpha-fetoprotein levels; kidney and liver function; and diet may be indicated.
  • CT or MRI liver scans for early diagnosis of scarring or cancer may be indicated.
  • Liver transplantation may be considered to prevent hepatocellular carcinoma.
  • For those identified after irreversible sequelae, assist in management of liver and kidney disease and support with developmental and educational interventions.

Specialty Care Collaboration

Initiate consultation and ongoing collaboration with gastroenterology and nephrology if the child is affected. A dietician may work with the family to devise an optimal approach to dietary management.


Information & Support

For Professionals

Tyrosinemia Type 1 (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular pathogenesis; from the University of Washington and the National Library of Medicine.

Resources for Tyrosinemia type 1 (Disease InfoSearch)
Compilation of information, articles, and links to support; from Genetic Alliance.

Tyrosinemia Type 1 (OMIM)
Information about clinical features, diagnosis, management, and molecular and population genetics; Online Mendelian Inheritance in Man, authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine

Utah Newborn Screening Program (UDOH)
Provides information about the program, related legislation, training for practices, and newborn conditions; Utah Department of Health.

For Parents and Patients


Utah Parent Center
A nonprofit organization that provides training, information, referral, and assistance to parents of children and youth with all disabilities including physical, mental, hearing, vision, learning, behavioral, and emotional. Staff consists primarily of parents of children and youth with disabilities.


Tyrosinemia Type 1 (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources; from the National Library of Medicine.

Tyrosinemia Type 1 - Information for Parents (STAR-G)
A fact sheet, written by a genetic counselor and reviewed by metabolic and genetic specialists, for families who have received an initial diagnosis of this newborn disorder; Screening, Technology and Research in Genetics.

Tyrosinemia Type 1 (GARD)
Includes information about symptoms, inheritance, diagnosis, finding a specialist, related diseases, and support organizations; Genetic and Rare Diseases Information Center of the National Center for Advancing Translational Sciences.

Center for Parent Information and Resources (DOE)
Parent centers in every state provide training to parents of children with disabilities and provide information about special education, transition to adulthood, health care, support groups, local conferences and other federal, state, and local services. See the "Find Your Parent Center Link" to find the parent center in your state; Department of Education, Office of Special Education.

Practice Guidelines

Chinsky JM, Singh R, Ficicioglu C, van Karnebeek CDM, Grompe M, Mitchell G, Waisbren SE, Gucsavas-Calikoglu M, Wasserstein MP, Coakley K, Scott CR.
Diagnosis and treatment of tyrosinemia type I: a US and Canadian consensus group review and recommendations.
Genet Med. 2017;19(12). PubMed abstract / Full Text


ACT Sheet for Tyrosine Normal/Elevated and SUAC Elevated (ACMG) (PDF Document 348 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical Genetics.

Confirmatory Algorithms Tyrosine Normal/Elevated and SUAC Elevated (ACMG) (PDF Document 156 KB)
An algorithm of the basic steps involved in determining the final diagnosis of an infant with a positive newborn screen; American College of Medical Genetics.

Confirmatory Algorithms Tyrosine SUAC Normal (ACMG) (PDF Document 146 KB)
An algorithm of the basic steps involved in determining the final diagnosis of an infant with a positive newborn screen; American College of Medical Genetics.

Services for Patients & Families in Utah (UT)

Genetics clinic services throughout the US can be found through the Genetics Clinic Services Search Engine (ACMG).

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.


Tyrosinemia Type 1 (clinicaltrials.gov)
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.

Helpful Articles

PubMed search for tyrosinemia type 1 and neonatal screening, last 5 years.

de Laet C, Dionisi-Vici C, Leonard JV, McKiernan P, Mitchell G, Monti L, de Baulny HO, Pintos-Morell G, Spiekerkötter U.
Recommendations for the management of tyrosinaemia type 1.
Orphanet J Rare Dis. 2013;8:8. PubMed abstract / Full Text
Developed by a European collaboration; recommendations may not apply to the United States, particularly as they relate to early diagnosis, since tyrosinemia is now routinely screened for in the US.

McKiernan PJ, Preece MA, Chakrapani A.
Outcome of children with hereditary tyrosinaemia following newborn screening.
Arch Dis Child. 2015;100(8):738-41. PubMed abstract

Authors & Reviewers

Initial publication: March 2007; last update/revision: July 2018
Current Authors and Reviewers:
Author: Nicola Longo, MD, Ph.D.
Authoring history
2011: first version: Nicola Longo, MD, Ph.D.A
AAuthor; CAContributing Author; SASenior Author; RReviewer

Page Bibliography

Schulze A, Lindner M, Kohlmuller D, Olgemoller K, Mayatepek E, Hoffmann GF.
Expanded newborn screening for inborn errors of metabolism by electrospray ionization-tandem mass spectrometry: results, outcome, and implications.
Pediatrics. 2003;111(6 Pt 1):1399-406. PubMed abstract