What is Ornithine Transcarbamylase Deficiency?

Ornithine transcarbamylase deficiency is a genetic disorder in which abnormally low levels of an important enzyme affect the liver's ability to convert ammonia to urea. As ammonia builds up in the liver and bloodstream, it leads to a serious medical condition called hyperammonemia. A person suffering from ornithine transcarbamylase deficiency may experience a number of neurological, pulmonary, and developmental complications. Doctors usually treat the condition in adults by administering medications to reduce the amount of ammonia in the body and suggesting a low-protein diet. When it appears in infancy, however, there is little doctors can do to prevent permanent brain damage, coma, and death.

Ammonia is a byproduct of normal metabolic processes that convert food to usable energy for cells. In healthy livers, ornithine transcarbamylase enzymes help to break down toxic ammonia compounds into a less noxious form called urea, which is expelled from the body in urine. Enzyme deficiencies are the result of genetic mutations on the X chromosome, though not all babies born with the condition experience problems right away. It is common for the condition to go unnoticed until it manifests in adolescence or adulthood.

An adult with a slight ornithine transcarbamylase deficiency may not experience any physical symptoms of hyperammonemia at all, though an individual with severely low levels of the enzyme can suffer from a host of health problems. Ornithine transcarbamylase deficiency can result in seizures, coordination problems, disorientation, and rapid, shallow breathing. As hyperammonemia worsens, it can lead to severe mood swings, anorexia, and brain damage. Some people suffer from mental retardation or slip into comas if hyperammonemia is not immediately identified and treated.

Infants who show immediate signs of ornithine transcarbamylase deficiency do not normally have a strong prognosis. The condition causes lethargy, vomiting, fluctuating body temperature, and malnutrition in newborns. Infants can experience liver damage, encephalitis, comas, and death within their first few months. Babies who do survive often suffer from permanent mental and physical disabilities.

Doctors usually diagnose ornithine transcarbamylase deficiency by looking for signs of hyperammonemia and taking blood and urine samples for laboratory analysis. Immediate treatment in the form of hemodialysis is usually necessary in infants and adults who exhibit severe symptoms. Hemodialysis entails inserting an intravenous catheter into the patient's arm to extract and filter tainted blood in his system. Injections of sodium benzoate are given to adults to help prevent new ammonia compounds from forming.

After initial treatment, doctors can discuss long-term management plans with their patients to make sure that enzyme deficiencies do not cause lasting problems. Patients are often placed on strict diets that consist of low protein, and high carbohydrates and lipids. Many people are referred to licensed nutritionists to help them plan their dietary routines. With careful monitoring by nutritionists and frequent checkups with physicians, most people diagnosed with ornithine transcarbamylase deficiency are able to lead normal, healthy lives.