HYPERAMMONEMIA DUE TO A DEFECT IN HEPATIC ORNITHINE TRANSCARBAMYLASE.

A 9-year-old girl with vomiting, changes in behavior, coma, and evidence of hepatic dysfunction at 3 1/2 years of age was found to have hyperammonemia and decreased activity of liver ornithine transcarbamylase. When her dietary protein was reduced, she had improvement in her clinical condition and a return to normal of all hepatic function indices. Despite a defect in an enzyme of ornithine metabolism, she did not have hyperaminoacidemia, specifically hyperornithinemia, even when she had hyperammonemia. When she ingested a large amount of ornithine (300 mg/kg) she developed hyperornithinemia and hyperornithinuria. She also had orotic aciduria despite having normal activities of red cell orotidylic decarboxylase and pyrophosphorylase. Treatment with a low protein diet and citric acid supplements has been successful in preventing hyperammonemia and promoting growth and development. [ABSTRACT FROM AUTHOR]