Tyrosinemia is caused by a lack of the enzyme needed to metabolize the amino acid tyrosine.
Symptoms include intellectual disability, liver and kidney disease, and body fluids that smell like boiled cabbage.
The diagnosis is based on a blood test.
A special diet and sometimes drugs may help some children.
Amino acids Branched-Chain Amino Acids Amino acid metabolism disorders are hereditary metabolic disorders. Hereditary disorders occur when parents pass the defective genes that cause these disorders on to their children. In most... read more are the building blocks of proteins and have many functions in the body. The body makes some of the amino acids it needs and gets others from food. Children with tyrosinemia are unable to completely break down (metabolize) the amino acid tyrosine. By-products of this amino acid build up, causing a variety of symptoms. These by-products also cause body fluids, such as urine and sweat, to smell like boiled cabbage.
There are different types of inherited disorders Inheritance of Single-Gene Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more . In tyrosinemia, both parents of the affected child carry a copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder. (See also Overview of Hereditary Metabolic Disorders Overview of Hereditary Metabolic Disorders Hereditary metabolic disorders are inherited genetic conditions that cause metabolism problems. Heredity is the passing of genes from one generation to the next. Children inherit their parents'... read more .)
In some states, the disorder is detected with newborn screening tests Newborn Screening Tests Many serious disorders that are not apparent at birth can nonetheless be detected by various screening tests. Early diagnosis and prompt treatment can reduce or prevent many disorders that may... read more .
There are two main types of tyrosinemia and a third, uncommon form:
Type III (rare)
Type I tyrosinemia
Type I tyrosinemia is most common among children of French-Canadian or Scandinavian descent.
Newborns may have liver failure. Older infants and children have dysfunction of the liver, kidneys, and nerves, resulting in irritability, rickets Hypophosphatemic Rickets Hypophosphatemic rickets is a disorder in which the bones become painfully soft and bend easily because the blood contains low levels of the electrolyte phosphate. (See also Introduction to... read more , or even liver failure Liver Failure Liver failure is severe deterioration in liver function. Liver failure is caused by a disorder or substance that damages the liver. Most people have jaundice (yellow skin and eyes), feel tired... read more and death.
Every state in the United States requires all newborns be screened for type I tyrosinemia with a blood test. To confirm the diagnosis, genetic testing or other tests of the blood and urine and a biopsy of the liver are done.
Restriction of the amino acids tyrosine and phenylalanine in the diet is recommended. A drug called nitisinone (also known as NTBC), which blocks production of toxic metabolites, may help children with type I tyrosinemia. Often, children with type I tyrosinemia require a liver transplant Liver Transplantation Liver transplantation is the surgical removal of a healthy liver or sometimes a part of a liver from a living person and then its transfer into a person whose liver no longer functions. (See... read more .
Type II tyrosinemia
Type II tyrosinemia is less common. Affected children sometimes have intellectual disability Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more and frequently develop sores on the skin and eyes.
Diagnosis of type II tyrosinemia is with a blood test. Other tests of the blood and urine and a biopsy of the liver may be done.
Treatment of type II tyrosinemia is by restricting tyrosine and phenylalanine in the diet.
Type III tyrosinemia
Type III tyrosinemia is very rare. Mild intellectual disability Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more , seizures, and periodic loss of balance and coordination are the most common symptoms.
Diagnosis of type III tyrosinemia is with a newborn blood screening test. Urine and blood tests may also be done if the screening is abnormal.
Treatment of type III tyrosinemia is by restricting tyrosine and phenylalanine in the diet.
The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
National Organization for Rare Disorders (NORD): This resource provides information to parents and families about rare diseases, including a list of rare diseases, support groups, and clinical trial resources.
Genetic and Rare Diseases Information Center (GARD): This resource provides and easy to understand information about rare or genetic diseases.
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