Urea cycle disorders are a group of disorders that affect the proteins that process ammonia and transport it out of the body. If ammonia is not excreted, it can be life threatening. The urea cycle is a vital part of providing nutrients to the body, building amino acids out of protein in the foods you eat. A waste product of the urea cycle is ammonia, which is turned into a substance called urea to be moved out of the body. There are 8 different urea cycle disorders named after the protein in the cycle that is not functional. When the urea cycle is unable to work properly, ammonia can build up in the body.
The 8 types of urea cycle disorders are:
Urea cycle disorders can be inherited by anyone.
Common symptoms of urea cycle disorders include:
Symptoms of urea cycle disorders may be present in babies as soon as they’re born, but not everyone gets diagnosed as an infant. Symptoms range from mild to severe, but symptoms that affect the brain can be life-threatening.
Genetic mutations cause urea cycle disorders. There’s a different genetic mutation responsible for each one of the dysfunctional proteins that can cause urea cycle disorders. To have urea cycle disorders, you have to inherit a genetic mutation from each parent.
Risk factors for urea cycle disorders are having parents with genetic mutations on the genes that encode the proteins that can cause urea cycle disorders.
Some newborns are diagnosed with urea cycle disorders at birth. However, many people are not diagnosed until they’re much older. Urea cycle disorders will be diagnosed by a medical provider who will take a thorough medical history and gain an understanding of your symptoms.
Blood and urine tests can confirm a diagnosis. Blood and urine tests may look for the absence or presence of certain amino acids. Your medical provider may also ask for a liver biopsy or genetic testing.
Complications of urea cycle disorders include developmental delays, seizures, and coma. Complications are preventable with effective management.
Treatment for urea cycle disorders focuses on lowering the amount of protein in the diet, dialysis to clear ammonia from the blood, taking certain medications for ammonia removal, and taking amino acid supplements.
Common foods to avoid if you live with a urea cycle disorder include fish, eggs, chicken, beef, soy, and beans. It’s important for individuals with urea cycle disorders to work with dieticians or nutritionists to ensure they are able to receive enough nutrients to grow normally since their diets are so protein restricted.
Treatment for urea cycle disorders is lifelong, with a normal life expectancy if the disorder is well-managed.
There is no prevention for urea cycle disorders, but people with urea cycle disorders can undergo genetic counselling to better understand the risk of having a child.