Tyrosinemia type III

Tyrosinemia type III is a rare metabolic disorder characterized by elevated levels of the amino acid tyrosine in the blood. This condition is caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase, which is involved in the breakdown of tyrosine.

Symptoms

The symptoms of Tyrosinemia type III can vary greatly among affected individuals. Some individuals may be asymptomatic, while others may experience neurological symptoms such as intellectual disability, seizures, and ataxia. Other symptoms may include hypertonia (increased muscle tone), dystonia (involuntary muscle contractions), and ocular disturbances.

Causes

Tyrosinemia type III is caused by mutations in the HPD gene, which provides instructions for producing the enzyme 4-hydroxyphenylpyruvate dioxygenase. This enzyme is involved in the second step of the breakdown of tyrosine. When this enzyme is deficient, tyrosine and its byproducts build up in the body, leading to the symptoms of Tyrosinemia type III.

Diagnosis

Diagnosis of Tyrosinemia type III is typically made through a combination of clinical examination and laboratory testing. Blood and urine tests can reveal elevated levels of tyrosine and its byproducts. Genetic testing can confirm a diagnosis by identifying mutations in the HPD gene.

Treatment

Treatment for Tyrosinemia type III typically involves a diet low in tyrosine and phenylalanine, another amino acid that the body converts into tyrosine. In some cases, medication may be used to help the body break down tyrosine.

Prognosis

The prognosis for individuals with Tyrosinemia type III varies depending on the severity of symptoms and the individual's response to treatment. With early diagnosis and appropriate treatment, many individuals with this condition can lead normal lives.

See also

• Tyrosinemia
• Metabolic disorder
• Amino acid disorder