N-acetylglutamate synthetase deficiency: diagnosis, management and follow-up of a rare disorder of ammonia detoxication.

We report the 9-year follow-up of a patient suffering from N-acetylglutamate synthetase deficiency, an urea cycle disorder leading to severe neonatal hyperammonaemia. Hitherto two patients from two families with this inborn error of metabolism had been observed. Our management consisted mainly of a protein-restricted diet and oral treatment with N-carbamylglutamate, an activator of carbamylphosphate synthetase, together with arginine or citrulline. The somatic development was normal whereas a moderate psychomotor retardation was diagnosed. The patient died after an episode of coma and prolonged generalized convulsions at the age of 9.5 years.