What are Urea Cycle Disorders?
A urea cycle disorder or UCD is an inborn error of liver metabolism. These genetic diseases are caused by the lack of or deficiency of one of six enzymes needed to break down the byproduct of protein metabolism, or ammonia, and remove it from the bloodstream. In severe cases affecting newborns, toxic ammonia builds up in the bloodstream and can cause brain damage, coma and death.
How rare are UCDs?
UCDs are an ultra orphan disease. The incidence is estimated at 1 in 10,000 births. Unfortunately, many cases go misdiagnosed or undiagnosed.
Does the disease vary?
The clinical presentation of UCDs can vary greatly. These differences are usually related to which enzyme is not fully functioning and whether the enzyme deficiency is partial or severe. Some children die in early infancy and others may not be diagnosed until adulthood.
What are the symptoms?
Infants with a complete enzyme deficiency often appear normal for the first days of life. Then, symptoms may be non-specific and include failure to feed, lethargy, low body temperature, extreme sleepiness, irritability, and vomiting. Without diagnosis and treatment, high levels of ammonia can lead to decreased muscle tone; hyperventilation or hypoventilation; hypothermia; seizures; neurologic posturing; and coma.
National Urea Cycle Disorders Foundation
National Organization for Rare Disorders
About clinical trials
Urea Cycle Disorders Consortium
Office of Rare Diseases Research