About Tyrosinemia Type I
Tyrosinemia type I (HT-I) is a rare autosomal recessive disorder of amino acid metabolism caused by deficiency of fumarylacetoacetate hydrolase (FAH), the final enzyme in the tyrosine degradation pathway. FAH deficiency results in accumulation of toxic intermediates, particularly fumarylacetoacetate and succinylacetone, which damage hepatocytes, proximal renal tubule cells, and nervous system tissue through oxidative stress and direct cellular toxicity.
The acute form presents within the first few months of life (often before age 6 months) with jaundice, hepatomegaly, liver dysfunction, coagulopathy, and rapid progression to cirrhosis and hepatic failure. The chronic form presents later (typically after age 6 months) with more gradual progression but inevitably leads to cirrhosis, progressive liver disease, and hepatocellular carcinoma development (cumulative risk approximately 37% by age 20 and >90% by age 30 without curative therapy).
Renal involvement manifests as renal tubular dysfunction (Fanconi syndrome) with proteinuria, hypokalemia, and progressive renal insufficiency. Neurologic crises with acute encephalopathy, seizures, developmental regression, and coma can occur unpredictably. Hepatocellular carcinoma risk is substantially elevated even in adequately treated patients.
Common Symptoms of Tyrosinemia Type I
Recognizing the signs of Tyrosinemia Type I early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Jaundice and liver dysfunction in infancy
- Hepatomegaly and cirrhosis development
- Failure to thrive
- Renal tubular dysfunction (Fanconi syndrome)
- Acute neurologic crisis with encephalopathy
- Growth failure and developmental delay
Who Tyrosinemia Type I Affects
Tyrosinemia Type I shows autosomal recessive inheritance, affecting males and females equally. The acute form typically presents within the first 6 months of life, though earlier presentation (first weeks of life) and later presentation (after age 6 months) occur. The chronic form may present in infancy or early childhood or occasionally later in the course of disease.
Geographic variation is notable: the condition shows highest prevalence in Scandinavian countries (particularly Finland and Sweden with founder mutations) and Quebec, Canada (with specific French-Canadian founder mutations; approximately 1 in 16,000 in some Quebec populations).
Worldwide prevalence is approximately 1 in 100,000-120,000. Genetic counseling indicates 25% recurrence risk for siblings of affected individuals. Prenatal diagnosis through genetic testing or enzyme assays in amniotic fluid/chorionic villus samples is possible.
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FDA-Approved Treatments for Tyrosinemia Type I
There is currently 1 FDA-approved medication for Tyrosinemia Type I. These therapies represent the current standard of care and may be used alongside or compared against investigational treatments in active clinical trials.
Source: openFDA drug labeling data. This list may not include all treatments. Always consult your doctor.
Side Effect Explorer
Real-world side effect reports from the FDA Adverse Event Reporting System (FAERS). Includes both FDA-approved drugs and investigational therapies from active clinical trials. Click any drug to see what patients reported.
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Genetic Testing
Genetic testing can confirm a diagnosis, guide treatment decisions, and identify family members who may be at risk.
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Trusted Tyrosinemia Type I Resources
Reputable organizations and medical references for learning more about Tyrosinemia Type I, including disease registries, foundation resources, and clinical guidelines.