Neonatal onset ornithine transcarbamylase deficiency: A retrospective analysis

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

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.

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.

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.