Tyrosinemia Type I

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Is there someone that I can talk to in order to understand more about Tyrosinemia Type I?

A genetic counselor can provide you with more information about Tyrosinemia Type I. Genetic counselors are healthcare professionals that have specialized training in medical genetics and counseling to provide personalized help to patients on their genetic health. If you are in the United States, you can find a genetic counselor by going to http://nsgc.org/p/cm/ld/fid=164. This page is the “Find a Genetic Counselor” tool on the National Society of Genetic Counselors webpage.

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Do carriers have symptoms of Tyrosinemia Type I?

What should I do if I do not have access to a Tyrosinemia specialist?

What are the risks associated with taking nitisinone if you have Tyrosinemia Type I?

Is there someone that can provide me with more information and help me with low-protein diet if I have Tyrosinemia Type I?

What does protein in my diet have to do with Tyrosinemia Type I?

What is the life expectancy of someone with Tyrosinemia Type I?

What is the frequency of Tyrosinemia Type I?

What data exists on the effects of Tyrosinemia Type I on the baby during pregnancy?

If I am pregnant and I have Tyrosinemia Type I, should I continue taking nitisinone?

If I have had a liver transplant, should I continue taking nitisinone if I have Tyrosinemia Type I?

How does nitisinone work in relation to Tyrosinemia Type I?

What symptoms do babies have if they were not detected to have Tyrosinemia Type I by newborn screening?

How frequent is liver cancer found in people who have Tyrosinemia Type I and are being treated with nitisinone and a low-protein diet?

Why is a liver transplant an effective treatment for Tyrosinemia Type 1?

There are three different types of Tyrosinemia. How is Type I different from Type II and Type III?

What are other names for nitisinone?

If I am taking nitisinone and have Tyrosinemia Type I, why do I still need to be on a low-protein diet?

Corneal crystals are a side effect of nitisinone. How do I know if I have these?

My doctor prescribes me a specialized formula/medical food to take in addition to my nitisinone. What is this and why do I need to take it if I have Tyrosinemia Type I?

What are good resources for me to learn more or for me to provide to others to learn more about Tyrosinemia Type I?

Is a positive newborn screen for Tyrosinemia Type I the same as a diagnosis?

Are there any patient registries for Tyrosinemia Type I?

Do carriers have symptoms of Tyrosinemia Type I?

Carriers (people with only one gene change) do not have symptoms or show signs of Tyrosinemia Type I.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
What should I do if I do not have access to a Tyrosinemia specialist?

Finding a genetic counselor and/or a medical geneticist near you would be an ideal way to make sure you have the information you need for your Tyrosinemia Type I to be managed correctly.

Make sure your primary care physician has the appropriate information on Tyrosinemia Type I in order to ensure that you are receiving the proper medical management.

What are the risks associated with taking nitisinone if you have Tyrosinemia Type I?

Nitisinone can increase the amount of tyrosine in a person’s body. Increased levels of tyrosine can lead to corneal crystals (deposits of tyrosine into a person’s eye). High levels of tyrosine can also cause skin on the palms and feet to become thickened. These side effects can be reversed when tyrosine levels are lowered.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
Is there someone that can provide me with more information and help me with low-protein diet if I have Tyrosinemia Type I?

A licensed dietician can help you with a low protein diet and make sure that you carry it out correctly. Specifically, dieticians that work in metabolic clinics have experience with specialized diets required by other metabolic disorders in addition to Tyrosinemia Type I. To find a metabolic dietitian specializing in diets for people with metabolic conditions, visit the GMDI Find a Metabolic Dietitian webpage.

What does protein in my diet have to do with Tyrosinemia Type I?

The main source for the body’s phenylalanine, an amino acid, comes from protein that we eat. Phenylalanine is broken down into tyrosine. The gene responsible for Tyrosinemia Type I is found in the pathway that breaks down tyrosine. Therefore, the more protein we eat, the more phenylalanine we have. The more phenylalanine we have, the more tyrosine we have as the phenylalanine gets broken down in the body. Symptoms from Tyrosinemia Type I occur when tyrosine is not broken down properly.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
What is the life expectancy of someone with Tyrosinemia Type I?

People with Tyrosinemia Type I are not expected to have a shorter lifespan than people without Tyrosinemia if they are on treatment. If children with Tyrosinemia Type I are not treated, their life expectancy differs depending on when their symptoms start (how severely they are affected). Approximately 30% of children diagnosed before 2 months of age and remain untreated live to 2 years of age. Approximately 75% of children diagnosed between 2 months and 6 months of age and remain untreated live to 2 years of age. Approximately 96% of children diagnosed after 6 months of age and remain untreated live to 2 years of age.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
What is the frequency of Tyrosinemia Type I?

Tyrosinemia Type I occurs in approximately 1 in 100,000 – 1 in 120,000 live births. This frequency is seen worldwide except in a few populations where it occurs more often. In Norway, the frequency is approximately 1 – 60,000 to 1 in 74,000 live births. In Quebec, Canada, the frequency is approximately 1 in 16,000.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
What data exists on the effects of Tyrosinemia Type I on the baby during pregnancy?

Little data exists on the effects of Tyrosinemia Type I during pregnancy. There have been three scientific papers published that outline three women who were treated with nitisinone during pregnancy and gave birth to three healthy babies. The children were noted to be developing normally. However, the effects of Tyrosinemia Type I and the effects of nitisinone are not entirely understood.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
If I am pregnant and I have Tyrosinemia Type I, should I continue taking nitisinone?

You should continue to take nitisinone during pregnancy. The risk of Tyrosinemia Type I on the development of the baby is not well understood. However, the risks associated with nitisinone on the development of the baby are not well understood either. Despite this, the risks of Tyrosinemia Type I to the baby and the mother are considered to be greater than the risks of nitisinone. As of January 11, 2016, nitisinone has not been shown to cause birth defects.

References
  • Kassel R, Sprietsma L, Rudnick D. Pregnancy in an NTBC-treated patient with hereditary tyrosinemia type I. Journal Of Pediatric Gastroenterology And Nutrition [serial online]. January 2015;60(1):e5-e7.
  • http://journals.lww.com/jpgn/Fulltext/2015/01000/Pregnancy_in_an_NTBC_Treated_Patient_With.31.aspx
If I have had a liver transplant, should I continue taking nitisinone if I have Tyrosinemia Type I?

Your doctor may prescribe you a low dose of nitisinone even though you have had a liver transplant. Tyrosinemia Type I can affect both the liver and the kidneys. For this reason, your doctor may prescribe you with nitisinone to prevent continued renal tubular dysfunction. However, not everyone who has had a liver transplant still takes nitisinone. Speak to your doctor to determine what is right for you.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
How does nitisinone work in relation to Tyrosinemia Type I?

Nitisinone is a drug that blocks an enzyme called parahydroxyphenylpyruvic acid dehydrogenase. This prevents the production of succinylacetone, the toxic compound responsible for the symptoms of Tyrosinemia Type I.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
What symptoms do babies have if they were not detected to have Tyrosinemia Type I by newborn screening?

Common symptoms of Tyrosinemia Type I in babies are:

  • Failure to thrive
  • Edema
  • Diarrhea/bloody stools
  • Vomiting
  • Enlarged liver
  • Tendency to bruise easily
  • Jaundice
  • Cabbage-like odor
References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
How frequent is liver cancer found in people who have Tyrosinemia Type I and are being treated with nitisinone and a low-protein diet?

Nitisinone began being offered at a treatment for Tyrosinemia Type I in the early 90s. Data on the long-term effects and effectiveness of this drug are limited because of this. It has been estimated that less than 5% of children who are started on nitisinone before the age of 2 develop liver cancer before 10 years of age. In one study where the oldest participant is 12 years old, there were no participants who developed liver cancer if they were placed on nitisinone before 1 month of age.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
Why is a liver transplant an effective treatment for Tyrosinemia Type 1?

When the enzyme fumarylacetoacetate hydrolase (FAH) is not working, tyrosine and toxic compounds build up as a result. The main toxic compound is succinylacetone, and it has been shown to accumulate in liver cells. When a person receives a liver transplant, they have essentially been given a liver where the enzyme FAH is working, and prevents the accumulation of succinylacetone.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
There are three different types of Tyrosinemia. How is Type I different from Type II and Type III?

Each type of Tyrosinemia is caused by a deficiency in different enzymes that are part of the pathway to breakdown tyrosine in the body. Tyrosinemia Type I is caused by a deficiency of fumaryacetoacetate hydrolase (FAH), and it is the most common and most severe type of Tyrosinemia.

Tyrosinemia Type II is caused by a deficiency of the enzyme tyrosine aminotransferase (TAT). This type of Tyrosinemia is the second most common. This type of Tyrosinemia does not affect the liver. Instead, symptoms affect the eyes, the skin, and development of the central nervous system.

Tyrosinemia Type III is caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase. Less than 20 people have been documented to have this type of Tyrosinemia. These people do not have liver involvement. Instead, symptoms include poor coordination and balance as well as seizures and intellectual disability.

References
  • http://www.babysfirsttest.org/newborn-screening/conditions/tyrosinemia-type-i
  • http://www.babysfirsttest.org/newborn-screening/conditions/tyrosinemia-type-ii
  • http://www.babysfirsttest.org/newborn-screening/conditions/tyrosinemia-type-iii
What are other names for nitisinone?

Other names for nitisinone include:

  • NTBC
  • Orfadin (marketed name by the company that makes nitisinone)
References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
If I am taking nitisinone and have Tyrosinemia Type I, why do I still need to be on a low-protein diet?

Nitisinone blocks the second step in the pathway that breaks down tyrosine so that toxic compounds responsible for the symptoms of Tyrosinemia Type I do no accumulate. This means that tyrosine cannot break down. If you are taking nitisinone and are not following a low-protein diet, tyrosine will accumulate in the body. This will cause side effects such as corneal crystals to develop. A low-protein diet prevents this from happening.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
Corneal crystals are a side effect of nitisinone. How do I know if I have these?

Corneal crystals cause a person’s eyes to be sensitive to light, itchy, and sometimes painful. If your eyes feel like this, notify your doctor as soon as possible.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
My doctor prescribes me a specialized formula/medical food to take in addition to my nitisinone. What is this and why do I need to take it if I have Tyrosinemia Type I?

The specialized formula/medical food that your doctor prescribes is an amino acid mixture. For Tyrosinemia Type I, this amino acid mixture does not have phenylalanine or tyrosine. People with Tyrosinemia are treated with a low-protein (low phenylalanine and low tyrosine) diet. This formula helps supplement other amino acids that the person may not be receiving when on this diet. Taking a medical formula ensures that the person with Tyrosinemia Type I is receiving all of the nutrients they need while on a low-protein diet.

References
  • Lisa Sniderman King, MSc, CGC, Cristine Trahms, MS, RD, and C Ronald Scott, MD
  • http://www.ncbi.nlm.nih.gov/books/NBK1515/
What are good resources for me to learn more or for me to provide to others to learn more about Tyrosinemia Type I?

Resources to teach others more about Tyrosinemia Type I include:

Is a positive newborn screen for Tyrosinemia Type I the same as a diagnosis?

A screening test identifies people who are at risk for having the disorder. This test looks at markers that are an indication of a disease, but a positive screening result can also happen because the sample was too small or was taken too early.

References
  • http://www.babysfirsttest.org/newborn-screening/conditions/tyrosinemia-type-i
Are there any patient registries for Tyrosinemia Type I?

A patient registries for Tyrosinemia Type I is Newborn Screen Connect (NBS-Tyrosinemia Connect):

https://nbs.patientcrossroads.org/.

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