Ornithine transcarbamylase deficiency in a girl with hyperkinetic behaviour

Congenital ornithine transcarbamylase deficiency (OTCD, OMIM 311250, Xp21.1) in humans results in hyperammonaemia with subsequent neurological symptoms including hypotonia, seizures and mental retardation. At the age of 3 years a hyperkinetic-hyperactive behaviour disorder of unknown origin was diagnosed in our female patient. The girl, ultimately diagnosed as having OTCD presented at the age of 6 years with an episode of feverassociated metabolic stroke including coma, epilepsy and further neurological symptoms due to hyperammonaemia. The pattern of plasma amino acids, the elevated level of orotic acid in urine and mutation analysis confirmed the diagnosis of OTCD. The possibility of early diagnosis and therapy of a disease which otherwise leads to severe neurological and psychiatric sequelae emphasizes the importance of precise evaluation of a possible organic cause for hyperkinetic-hyperactive behaviour disorders. This case of late-onset OTCD demonstrates that total recovery is possible even after a long comaepisode with slow reconvalescence. (J Pediatr Neurol 2004; 2(2): 97-100).