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Tyrosinemia type I

(TIE-ruh-sin-EE-mee-uh • type • 1)

General Condition Information

Other Names

  • Tyrosinemia
  • Tyrosinemia I
  • Tyrosinemia type 1
  • Tyrosinemia type I (Hepatorenal)
  • Tyrosinemia, type 1
  • Tyrosinemia, type I

Condition Type

Birth Prevalence

  • It is estimated that fewer than 40 babies are born with this condition each year in the United States. 
  • Visit GeneReviews to learn more about how often this condition occurs.

Screening Finding

Increased succinylacetone (SUAC)

What is tyrosinemia type i

Tyrosinemia type I is an inherited (genetic) condition that prevents the body from processing proteins correctly. Your body breaks down the protein that you eat into amino acids. Your body then uses those amino acids to make other proteins that it needs to function.

There are several enzymes in your body that break down an amino acid called tyrosine. The process of breaking down tyrosine happens in multiple steps. Each step needs a specific enzyme. In tyrosinemia, one of these enzymes is not working well. Either the body does not make enough enzyme, or does not make the enzyme correctly. People with tyrosinemia have trouble with the process of breaking down tyrosine. 

There are different types of tyrosinemia: type I, type II, and type III. The type of tyrosinemia that your baby has depends on which step in the breakdown process is not working.

In tyrosinemia type I, the enzyme fumarylacetoacetate hydrolase (FAH) is not working. Without working FAH, the last step of breaking down tyrosine slows or shuts down. When the last step of breaking down tyrosine slows down or stops, a toxin called succinylacetone can form.

Without treatment, high levels of succinylacetone can damage the liver and kidneys. This damage can lead to the signs and symptoms of the condition.

There are two forms of tyrosinemia type I: acute and chronic. The form your baby has depends on how well their body can break down tyrosine. The acute form is more severe and shows up earlier in life. In severe cases, this condition can lead to serious health problems or death if not treated early.

Newborn Screening and Follow-Up

Condition Details

Treatment and Management

It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.

Treatments may include the following:

  • Diet low in protein
  • Special formulas and foods
  • Medication called nitisinone that helps stop succinylacetone from building up
  • Vitamin D and carnitine supplementation in some cases

Children who receive early intervention and treatment for tyrosinemia type I can have healthy growth and development. Treatment is very important for lowering the chance of liver and kidney problems.

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