How to diagnose and treat Tyrosinemia type 1

Introduction: Tyrosinemia type 1 is an autosomal recessive disorder that affects approximately 1 in 100,000 births worldwide . The disease is caused by a deficiency of Fumarylacetoacetate enzyme activity in tyrosine catabolism pathway.Tyrosinemia type 1 may be presented with acute liver failure in neonatal period or later with growth failure, hypophosphatemic rickets due to renal tubular dysfunction and peripheral neuropathy. Hepatoma or hepatocellular carcinoma can occur in untreated children.Materials & Methods: Affected newborn can be detected by screening test at birth or may later be diagnosed with diagnostic tests in symptomatic patients. Elevated tyrosine, phenylalanine or methionine in the blood suggest tyrosinemia type1 but measurement of succinylacetone in blood or urine is more sensitive and specific .although alphafeto protein increased, it’s not specific. Other biochemical findings included raised prothrombin time and partial thromboplastin time and increased urinary -ALA. Molecular genetic studies can be helpful for prenatal diagnosis or family screening.Results: After confirming the diagnosis, Nitisinone (NTBC) treatment should begin immediately. NTBC blocks Parahydroxyphenylpyruvic acid dioxygenase ,so prevent accumulation of succinylacetone. Since NTBC increases the serum level of tyrosine, restriction of tyrosine intake is necessary. All patients must be monitored for long term complications. All siblings of patient with tyrosinemia type 1 should be screened with blood or urine succinylacetone measurement after birth to initiate therapy as soon as possible.Conclusion & discussion: Measurement of blood /urine succinylacetone is sensitive and specific test for tyrosinemia type 1 screening. After diagnosis, Combined NTBC treatment and tyrosine restrict intake should be start as soon as possible .

کلیدواژه ها:

Tyrosinemia ، succinylacetone ، metabolic