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|OMIM||276700 276600 276710|
|DiseasesDB||13478 13486 29836|
Tyrosinemia is inherited in an autosomal recessive pattern. There are three types of tyrosinemia, each with distinctive symptoms and caused by the deficiency of a different enzyme.
Type I tyrosinemia
Type I tyrosinemia (OMIM 276700) is the most severe form of this disorder and is caused by a shortage of the enzyme fumarylacetoacetate hydrolase (EC 22.214.171.124), encoded by the gene FAH found on chromosome number 15. Fumarylacetoacetate hydrolase is the last in a series of five enzymes needed to break down tyrosine. Symptoms of type I tyrosinemia usually appear in the first few months of life and include failure to gain weight and grow at the expected rate (failure to thrive), diarrhea, vomiting, yellowing of the skin and whites of the eyes (jaundice), cabbagelike odor, and increased tendency to bleed (particularly nosebleeds). Type I tyrosinemia can lead to liver and kidney failure, problems affecting the nervous system, and an increased risk of liver cancer.
Worldwide, type I tyrosinemia affects about 1 person in 100,000. This type of tyrosinemia is much more common in Quebec, Canada. The overall incidence in Quebec is about 1 in 16,000 individuals. In the Saguenay-Lac-Saint-Jean region of Quebec, type 1 tyrosinemia affects 1 person in 1,846.
Type II tyrosinemia
Type II tyrosinemia (OMIM 276600) is caused by a deficiency of the enzyme tyrosine aminotransferase (EC 126.96.36.199), encoded by the gene TAT. Tyrosine aminotransferase is the first in a series of five enzymes that converts tyrosine to smaller molecules, which are excreted by the kidneys or used in reactions that produce energy. This form of the disorder can affect the eyes, skin, and mental development. Symptoms 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. About half of individuals with type II tyrosinemia are also mentally retarded. Type II tyrosinemia occurs in fewer than 1 in 250,000 individuals.
Type III tyrosinemia
Type III tyrosinemia (OMIM 276710) is a rare disorder caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase (EC 188.8.131.52), encoded by the gene HPD. This enzyme is abundant in the liver, and smaller amounts are found in the kidneys. It is one of a series of enzymes needed to break down tyrosine. Specifically, 4-hydroxyphenylpyruvate dioxygenase converts a tyrosine byproduct called 4-hydroxyphenylpyruvate to homogentisic acid. Characteristic features of type III tyrosinemia include mild mental retardation, seizures, and periodic loss of balance and coordination (intermittent ataxia). Type III tyrosinemia is very rare; only a few cases have been reported.
Treatment varies depending on the specific type. A low protein diet may be required in the management of tyrosinemia. Recent experience with NTBC has shown to be very effective.
- For a thorough scientific overview of hypertyrosinemia, one can consult chapter 79 of OMMBID. For more online resources and references, see inborn errors of metabolism.
- Charles Scriver, Beaudet, A.L., Valle, D., Sly, W.S., Vogelstein, B., Childs, B., Kinzler, K.W. (Accessed 2007). The Online Metabolic and Molecular Bases of Inherited Disease. New York: McGraw-Hill. - Summaries of 255 chapters, full text through many universities. There is also the OMMBID blog.
amino-acids Phenylketonuria - Alkaptonuria - Ochronosis - Tyrosinemia - Maple syrup urine disease - Propionic acidemia - Methylmalonic acidemia - Isovaleric acidemia - Primary carnitine deficiency - Cystinuria - Cystinosis - Hartnup disease - Homocystinuria - Citrullinemia - Hyperammonemia - Glutaric acidemia type 1
carbohydrates Lactose intolerance - Glycogen storage disease (type I, type II, type III, type IV, type V), Fructose intolerance, Galactosemia
Lipid storage disorders Gangliosidosis - GM2 gangliosidoses (Sandhoff disease, Tay-Sachs disease) - GM1 gangliosidoses - Mucolipidosis type IV - Gaucher's disease - Niemann-Pick disease - Farber disease - Fabry's disease - Metachromatic leukodystrophy - Krabbe disease - Neuronal ceroid lipofuscinosis - Batten disease - Cerebrotendineous xanthomatosis - Wolman disease - Cholesteryl ester storage disease
List of fatty acid metabolism disorders - Hyperlipidemia - Hypercholesterolemia - Familial hypercholesterolemia - Xanthoma - Combined hyperlipidemia - Lecithin cholesterol acyltransferase deficiency - Tangier disease - Abetalipoproteinemia
mineral metabolism Disorders of calcium metabolism - Hypophosphatemia - Hypophosphatasia - Wilson's disease - Menkes disease - Hypermagnesemia - Hypomagnesemia - Hypercalcaemia - Hypocalcaemia
fluid, electrolyte and acid-base balance Electrolyte disturbance - Hypernatremia - Hyponatremia - Respiratory acidosis - Metabolic acidosis - Lactic acidosis - Hypervolemia - Hypokalemia - Hyperkalemia - Mixed disorder of acid-base balance - Hyperchloremia - Hypochloremia - Dehydration
porphyrin and bilirubin Acatalasia - Gilbert's syndrome - Crigler-Najjar syndrome - Dubin-Johnson syndrome - Rotor syndrome - Porphyria (Acute intermittent porphyria, Gunther's disease, Porphyria cutanea tarda, Erythropoietic protoporphyria, Hepatoerythropoietic porphyria, Hereditary coproporphyria, Variegate porphyria)
glycosaminoglycan Mucopolysaccharidosis - Hurler syndrome - Hunter syndrome - Sanfilippo syndrome - Morquio syndrome
glycoprotein I-cell disease - Pseudo-Hurler polydystrophy - Aspartylglucosaminuria - Fucosidosis - Alpha-mannosidosis - Sialidosis
other Alpha 1-antitrypsin deficiency - Cystic fibrosis - Familial Mediterranean fever - Lesch-Nyhan syndrome