tyrosinemia (redirected from Hereditary Tyrosinemias)

tyrosinemia /ty·ro·sin·e·mia/ (ti″ro-sĭ-ne´me-ah) an aminoacidopathy of tyrosine metabolism with elevated blood levels of tyrosine and urinary excretion of tyrosine and related metabolites. Type I shows inhibition of some liver enzymes and renal tubular function. Type II is marked by crystallization of the accumulated tyrosine in the epidermis and cornea and is frequently accompanied by mental retardation. Neonatal t. is asymptomatic, transitory, and may result in mild mental retardation. The fourth type is hawkinsinuria .

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ty·ro·si·ne·mi·a (tr-s-nm-)

n.

An inherited disorder of tyrosine metabolism marked by an increase in the concentration of tyrosine in the blood, an increase in urinary excretion of tyrosine and related compounds, hepatosplenomegaly, nodular cirrhosis of the liver, multiple renal tubular reabsorptive defects, and vitamin D-resistant rickets.

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tyrosinemia

[tī′rōsinē′mē·ə]

Etymology: Gk, tyros + haima, blood

1 a benign, transient condition of the newborn, especially premature infants, in which an excessive amount of the amino acid tyrosine is found in the blood and urine. The disorder is caused by an anomaly in amino acid metabolism, usually delayed development of the enzymes necessary to metabolize tyrosine, and is controlled by dietary measures and vitamin C therapy. The metabolic defect disappears with treatment, or it may disappear spontaneously. Also called neonatal tyrosinemia.

2 a hereditary disorder involving an inborn error of metabolism of the amino acid tyrosine. The condition, which is transmitted as an autosomal-recessive trait, is caused by an enzyme deficiency and results in liver failure or hepatic cirrhosis, renal tubular defects that can lead to renal rickets and renal glycosuria, generalized aminoaciduria, and mental retardation. Treatment consists of a diet low in tyrosine and phenylalanine and high in vitamin C. In severe cases prognosis is extremely poor, and a liver transplantation may be the only lifesaving measure. Also called hereditary tyrosinemia.

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tyrosinemia (tī´rōsinē´mē),

n a genetic disorder of amino acid metabolism in which tyrosine acid accumulates in the blood and urine at abnormally high levels; seen primarily in infants born prematurely; may respond to a low-protein diet and the administration of synthetic amino acids.

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tyrosinemia

an excess of tyrosine in the blood. Several different types with varying clinical features occur in humans. A syndrome of dermatitis and keratoconjunctivitis resembling tyrosinemia type II of humans (Richner-Hanhart syndrome) occurs in rats fed a diet high in tyrosine, in mink as an inherited disorder (called also pseudodistemper) and it has been reported in a dog.