Tyrosinemia Type I
What is Tyrosinemia Type I?
Tyrosinemia Type I is a rare genetic disorder that affects how your body breaks down an amino acid called tyrosine. Amino acids are building blocks that help make proteins your body needs to function. When you have this condition, your liver cannot properly process tyrosine because of a missing enzyme.
This missing enzyme is called fumarylacetoacetate hydrolase. Without it, toxic substances build up in your liver and kidneys. These toxic substances damage liver cells over time and can lead to serious liver problems. The condition appears most often in infants but can sometimes show up later in childhood.
Tyrosinemia Type I is inherited, which means it passes from parents to children through genes. Both parents must carry the gene mutation for a child to develop the condition. Early detection and treatment can prevent severe liver damage and improve long-term health outcomes.
Symptoms
- Poor weight gain or failure to thrive in infants
- Vomiting and diarrhea
- Enlarged liver or spleen
- Yellowing of the skin and eyes, known as jaundice
- Cabbage-like odor to the body
- Fever without infection
- Irritability or decreased activity
- Swollen belly due to fluid buildup
- Bleeding or bruising easily
- Pain in the abdomen
Some children with milder forms may have few symptoms early on. This makes blood testing important for early detection, especially in families with a history of the condition.
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Causes and risk factors
Tyrosinemia Type I is caused by mutations in the FAH gene. This gene provides instructions for making the enzyme that breaks down tyrosine. When both copies of the gene are mutated, the enzyme does not work properly. Toxic substances called fumarylacetoacetate and maleylacetoacetate then build up and damage liver and kidney cells.
The condition follows an autosomal recessive inheritance pattern. This means both parents must be carriers of the mutated gene for their child to develop the disorder. Carriers typically have no symptoms themselves. The condition is more common in certain populations, including people of French-Canadian, Scandinavian, and Finnish descent. A family history of the condition increases risk significantly.
How it's diagnosed
Tyrosinemia Type I is diagnosed through a combination of newborn screening, blood tests, urine tests, and genetic testing. Many states include screening for this condition in their newborn testing programs. Blood tests measure levels of tyrosine and another amino acid called methionine. Urine tests look for specific toxic substances that build up when the enzyme is missing.
Alanine Aminotransferase or ALT is a liver enzyme that becomes elevated when liver cells are damaged. Regular ALT testing helps monitor the severity of liver injury in people with Tyrosinemia Type I. It also helps doctors assess how well treatment is working and when liver transplant may be needed. Rite Aid offers ALT testing as part of our flagship blood panel, making it easier to monitor liver health at Quest Diagnostics locations nationwide.
Treatment options
- Nitisinone medication, which blocks the production of toxic substances
- Low-protein diet that restricts tyrosine and phenylalanine intake
- Special medical formulas designed for metabolic disorders
- Regular monitoring with blood tests to check liver function
- Vitamin and mineral supplements as recommended by a metabolic specialist
- Liver transplant in severe cases or when medication is not effective
- Screening for liver cancer, as risk increases with this condition
- Working with a registered dietitian who specializes in metabolic conditions
Treatment must continue throughout life. Most people with Tyrosinemia Type I who start nitisinone early and follow a restricted diet can prevent serious liver damage and live healthy lives.
Concerned about Tyrosinemia Type I? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
Tyrosinemia Type I is a rare genetic disorder that prevents the body from breaking down the amino acid tyrosine properly. A missing enzyme causes toxic substances to build up and damage the liver and kidneys. The condition is inherited from both parents and typically appears in infancy or early childhood.
Early signs include poor weight gain, vomiting, diarrhea, and an enlarged liver. Babies may also develop jaundice, which causes yellowing of the skin and eyes. Some infants have a distinctive cabbage-like body odor. Irritability, fever without infection, and a swollen belly are also common warning signs.
The condition follows an autosomal recessive pattern, meaning a child must inherit one mutated gene from each parent to develop the disorder. Parents who carry one mutated gene typically have no symptoms themselves. If both parents are carriers, each child has a 25% chance of having Tyrosinemia Type I.
Yes, blood tests play a key role in diagnosis and monitoring. Newborn screening tests check for elevated tyrosine levels. ALT blood tests measure liver enzyme levels and help track liver damage over time. Regular blood monitoring helps doctors assess treatment effectiveness and detect complications early.
Elevated ALT indicates that liver cells are being damaged by toxic substances that build up in this condition. Higher ALT levels suggest more severe liver injury. Monitoring ALT helps doctors determine if treatment with nitisinone is working and whether more aggressive intervention like liver transplant may be needed.
Nitisinone is a medication that blocks the production of toxic substances in people with Tyrosinemia Type I. It prevents fumarylacetoacetate from forming, which reduces liver and kidney damage. When started early and combined with dietary restrictions, nitisinone can prevent serious complications and allow people to live healthy lives.
Yes, a low-protein diet that restricts tyrosine and phenylalanine is essential for managing the condition. People typically use special medical formulas designed for metabolic disorders. Working with a dietitian who specializes in metabolic conditions helps ensure proper nutrition while keeping amino acid levels safe. The diet must continue throughout life.
There is no cure, but the condition can be managed effectively with early treatment. Nitisinone medication combined with dietary restrictions can prevent liver damage and allow normal development. In severe cases where medication is not effective, liver transplant can provide a functional enzyme. Lifelong monitoring and treatment are necessary.
Tyrosinemia Type I significantly increases the risk of developing hepatocellular carcinoma, a type of liver cancer. The toxic substances that damage liver cells can also trigger abnormal cell growth. Regular screening with imaging and blood tests helps detect cancer early when it is most treatable.
Testing frequency depends on age, treatment response, and disease severity. Infants and young children may need monthly or quarterly blood tests to monitor liver function and amino acid levels. Adults on stable treatment may test every few months. Your metabolic specialist will recommend a personalized monitoring schedule based on your individual needs.