Tyrosinemia Type I (HT-I) Clinical Trials and Treatments

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 most common symptoms of Tyrosinemia Type I include Jaundice and liver dysfunction in infancy, Hepatomegaly and cirrhosis development, Failure to thrive, Renal tubular dysfunction (Fanconi syndrome), Acute neurologic crisis with encephalopathy, among others. Tyrosinemia Type I affects approximately 1 in 100,000 to 120,000 people; highest in Quebec and Scandinavia. Symptoms can range from mild to severe and may vary between individuals.

Trial Friend lists all active clinical trials for Tyrosinemia Type I from ClinicalTrials.gov, with eligibility criteria translated into plain English. Patients can filter by trial phase and recruitment status, search by location, and use the Match Me tool to score trials against their profile. Nitisinone (NTBC, 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione), an inhibitor of 4-hydroxyphenylpyruvate dioxygenase (the enzymatic step before FAH-requiring metabolism), is transformative therapy that prevents accumulation of toxic metabolites. Combined with strict dietary restriction of tyrosine and phenylalanine (target plasma tyrosine 300-600 umol/L to avoid phototoxicity while maintaining effective FAH inhibition), nitisinone dramatically improves liver and renal function, prevents neurologic crises, and dramatically improves prognosis and life expectancy.

As of September 2026, Trial Friend's curated drug index does not include an FDA-approved treatment specific to Tyrosinemia Type I. The Treatments section of this page checks FDA drug labels live and lists any approved drug whose label names the condition, and the trials listed below cover the investigational options.

Tyrosinemia Type I is caused by variants in the FAH gene. Type I is FAH (fumarylacetoacetate hydrolase) deficiency; TAT and HPD cause the distinct types II and III.

It is inherited in an autosomal recessive pattern: both parents are usually unaffected carriers, and each pregnancy has a 1 in 4 chance of an affected child. The condition affects approximately 1 in 100,000 to 120,000 people; highest in Quebec and Scandinavia. Genetic testing confirms the diagnosis.

Yes. Genetic testing for Tyrosinemia Type I looks at the FAH gene. Type I is FAH (fumarylacetoacetate hydrolase) deficiency; TAT and HPD cause the distinct types II and III.

It is inherited in an autosomal recessive pattern: both parents are usually unaffected carriers, and each pregnancy has a 1 in 4 chance of an affected child.

A confirmed variant establishes the diagnosis and is often required to enroll in gene-specific trials. The labs currently offering the test are listed in the Genetic Testing section of this page, pulled live from the NIH Genetic Testing Registry. A genetic counselor can help interpret the result and decide which relatives should be tested.

Eligibility for Tyrosinemia Type I clinical trials depends on factors like age, diagnosis, treatment history, and overall health. Each trial sets its own inclusion and exclusion criteria. Trial Friend translates these requirements from medical language into plain English so patients can review them more easily. The Match Me tool can score your profile against active trials to help identify studies that may be a fit.

Participating in a Tyrosinemia Type I clinical trial typically involves scheduled visits, medical tests, and close monitoring by a research team. Depending on the study phase, you may receive an investigational treatment, a placebo, or the current standard of care. Trials may last from a few weeks to several years. Study participation is voluntary, and you can withdraw at any time.