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The genetic tyrosinemias.
Am J Med Genet C Semin Med Genet 2006; 142C(2):121-6AJ

Abstract

The genetic tyrosinemias are characterized by the accumulation of tyrosine in body fluids and tissues. The most severe form of tyrosinemia, Type I, is a devastating disorder of childhood that causes liver failure, painful neurologic crises, rickets, and hepatocarcinoma. This disorder is caused by a deficiency of fumarylacetoacetate hydrolase (FAH). If untreated, death typically occurs at less than 2 years of age, with some chronic forms allowing longer survival. It has a prevalence of about 1 in 100,000 newborns in the general population. Oculocutaneous tyrosinemia, Type II, is caused by a deficiency of tyrosine aminotransferase (TAT). It clinically presents with hyperkeratotic plaques on the hands and soles of the feet and photophobia due to deposition of tyrosine crystals within the cornea. Tyrosinemia Type III is an extremely rare disorder caused by a deficiency of 4-hydroxyphenylpyruvic dioxygenase. It has been associated with ataxia and mild mental retardation. These disorders are diagnosed by observing elevated tyrosine by plasma amino acid chromatography and characteristic tyrosine metabolites by urine organic acid analysis. In tyrosinemia Type I, methionine is also elevated, reflecting impaired hepatocellular function. Urine organic acids show elevated p-hydroxy-phenyl organic acids in each type of tyrosinemia, and the pathognomic succinylacetone in tyrosinemia Type I. Diagnosis can be confirmed by enzyme or molecular studies in tyrosinemia Type I. Therapy consists of a diet low in phenylalanine and tyrosine for each of the tyrosinemias and 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC) for tyrosinemia Type I.

Authors+Show Affiliations

Department of Pediatrics, University of Washington, Seattle, WA 98195, USA. crscott@u.washington.edu

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.
Review

Language

eng

PubMed ID

16602095

Citation

Scott, C Ronald. "The Genetic Tyrosinemias." American Journal of Medical Genetics. Part C, Seminars in Medical Genetics, vol. 142C, no. 2, 2006, pp. 121-6.
Scott CR. The genetic tyrosinemias. Am J Med Genet C Semin Med Genet. 2006;142C(2):121-6.
Scott, C. R. (2006). The genetic tyrosinemias. American Journal of Medical Genetics. Part C, Seminars in Medical Genetics, 142C(2), pp. 121-6.
Scott CR. The Genetic Tyrosinemias. Am J Med Genet C Semin Med Genet. 2006 May 15;142C(2):121-6. PubMed PMID: 16602095.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The genetic tyrosinemias. A1 - Scott,C Ronald, PY - 2006/4/8/pubmed PY - 2006/6/21/medline PY - 2006/4/8/entrez SP - 121 EP - 6 JF - American journal of medical genetics. Part C, Seminars in medical genetics JO - Am J Med Genet C Semin Med Genet VL - 142C IS - 2 N2 - The genetic tyrosinemias are characterized by the accumulation of tyrosine in body fluids and tissues. The most severe form of tyrosinemia, Type I, is a devastating disorder of childhood that causes liver failure, painful neurologic crises, rickets, and hepatocarcinoma. This disorder is caused by a deficiency of fumarylacetoacetate hydrolase (FAH). If untreated, death typically occurs at less than 2 years of age, with some chronic forms allowing longer survival. It has a prevalence of about 1 in 100,000 newborns in the general population. Oculocutaneous tyrosinemia, Type II, is caused by a deficiency of tyrosine aminotransferase (TAT). It clinically presents with hyperkeratotic plaques on the hands and soles of the feet and photophobia due to deposition of tyrosine crystals within the cornea. Tyrosinemia Type III is an extremely rare disorder caused by a deficiency of 4-hydroxyphenylpyruvic dioxygenase. It has been associated with ataxia and mild mental retardation. These disorders are diagnosed by observing elevated tyrosine by plasma amino acid chromatography and characteristic tyrosine metabolites by urine organic acid analysis. In tyrosinemia Type I, methionine is also elevated, reflecting impaired hepatocellular function. Urine organic acids show elevated p-hydroxy-phenyl organic acids in each type of tyrosinemia, and the pathognomic succinylacetone in tyrosinemia Type I. Diagnosis can be confirmed by enzyme or molecular studies in tyrosinemia Type I. Therapy consists of a diet low in phenylalanine and tyrosine for each of the tyrosinemias and 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC) for tyrosinemia Type I. SN - 1552-4868 UR - https://www.unboundmedicine.com/medline/citation/16602095/The_genetic_tyrosinemias_ L2 - https://doi.org/10.1002/ajmg.c.30092 DB - PRIME DP - Unbound Medicine ER -