Tyrosinemia type I

Tyrosinemia type I is a rare genetic disorder characterized by disruptions in the metabolic pathway of the amino acid tyrosine. This condition is the most severe form of tyrosinemia and is caused by a deficiency of the enzyme fumarylacetoacetate hydrolase (FAH), which is necessary for the final step in the breakdown of tyrosine.

Symptoms

The symptoms of Tyrosinemia type I usually become apparent in the first few months of life. They may 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), cabbage-like odor, and increased tendency to bleed (particularly nosebleeds). Neurological crises characterized by changes in mental state, reduced sensation in the arms and legs (peripheral neuropathy), abdominal pain, respiratory failure, and high blood pressure may also occur.

Causes

Tyrosinemia type I is caused by mutations in the FAH gene. This gene provides instructions for making an enzyme called fumarylacetoacetate hydrolase, which is involved in the final step of breaking down the amino acid tyrosine. Mutations in the FAH gene disrupt the function of the enzyme, preventing the body from breaking down tyrosine properly. This leads to a buildup of tyrosine and its byproducts in the body, which can cause damage to the liver, kidneys, and nervous system.

Diagnosis

Diagnosis of Tyrosinemia type I is based on the symptoms, laboratory testing showing elevated tyrosine levels in the blood and urine, and confirmed by genetic testing.

Treatment

Treatment for Tyrosinemia type I involves a diet low in tyrosine and phenylalanine, medications to reduce the production and absorption of tyrosine, and liver transplantation in severe cases.

Prognosis

The prognosis for individuals with Tyrosinemia type I varies. With early diagnosis and appropriate treatment, individuals with this condition can lead a relatively normal life. However, without treatment, severe complications such as liver and kidney failure can occur.

See also

• Tyrosinemia
• Metabolic disorder
• Genetic disorder
• Amino acid

References

Tyrosinemia type I Resources
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