Neonatal onset ornithine transcarbamylase deficiency: A retrospective analysis.

Objective: A retrospective analysis of 74 cases of neonatal-onset ornithine transcarbamylase (OTC) deficiency.

Methods: The medical records of 74 of the 128 male patients referred to this center with neonatal onset OTC from 1976 to 1996 were available and analyzed.

Results: Initial symptoms of OTC deficiency were nonspecific and included feeding difficulties, lethargy, and "respiratory distress"; vomiting was infrequent. Respiratory alkalosis was regularly observed; the mean pH and pCO2 were 7.5 and 24 torr, respectively. Early consideration of a metabolic disorder in those neonates with a negative family history was only 9%. Sepsis was initially misdiagnosed in 50% of the cases. For all patients the mean age at onset was 63 hours. Survival was better among those who had later onset, later diagnostic studies, and diagnosis. Apart from 1 patient whose peak ammonium level was 400 micromol/L, all surviving patients had severe developmental delay.

Conclusions: OTC deficiency should be suspected in term infants who have early signs of encephalopathy, particularly after the first 24 hours; a respiratory alkalosis is pathognomic of urea cycle disorders. Severe developmental delay is the usual outcome of OTC deficiency.