What is Hereditary Tyrosinemia Type 1 (HT-1)?

Hereditary Tyrosinemia Type 1, often referred to as HT-1, is an ultra-rare disorder that leaves a person unable to fully break down the amino acid tyrosine.

This causes a dangerous build-up of toxic metabolites in the body – which can lead to serious liver and kidney problems – those affected require a special diet and medication (nitisinone, sometimes known as NTBC) to control the disorder. It is estimated to affect approximately 1 in 100,000 people across the world.1

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What causes Hereditary Tyrosinemia Type 1?

Hereditary Tyrosinemia Type 1 is a lifelong disorder. It is an autosomal recessive genetic condition, which means the baby inherits a defective gene from each parent. Unaffected adults are often unaware they carry a defective gene until they have an affected child. People born with Hereditary Tyrosinemia Type 1 cannot metabolize the amino acid tyrosine, meaning they are missing an essential enzyme that helps to break down protein in the food they eat.


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How is the condition diagnosed?

In the US Hereditary Tyrosinemia Type 1 is mostly diagnosed at birth. Newborn screening typically involves a heel stick blood test. However, a positive screening result may not be definitive. Healthcare providers may order additional blood and urine tests to confirm the diagnosis. Early testing gives the opportunity to start treatment as early as possible, minimizing the risk of further complications.