| Phenotype details |
born at term by Caesarian section (because of placenta previa) as the youngest of five children to first-cousin consanguineous Pakistani parents. 13m, after unremarkable development, he presented with a 1-day history of visual unresponsiveness. At admission, he was encephalopathic with hyperammonemia (258 μmol/L), hyperlactatemia (4.9 mmol/L), with a compensated metabolic acidosis (pH 7.43, pCO224.8 mm Hg, HCO3 -14 mEq/l). His encephalopathy improved after 48 hours of intravenous fluids and antibiotics administered for presumed meningo-encephalitis (cultures were negative). At the age of 16 months, he had a similar crisis; there were no signs of liver injury. Further metabolic investigations are shown in Table 1. Sodium benzoate and L-arginine were initiated with improvement after 48 hours, and he was discharged on a protein-restricted diet. Urea cycle defects (OTC [MIM 311250], CPS1 [MIM 237300], NAGS [MIM 2373100] deficiencies), and PC [MIM 266150], citrin [MIM 605814], and biotinidase [MIM 253260] deficiencies were excluded by molecular or enzymatic analyses. Following these two crises, he has demonstrated good developmental progress with only minor learning difficulties (no formal testing was available). He continues to have infrequent episodes of vomiting and ketoacidosis without hyperammonemia or lactic acidosis; the frequency of these episodes has not increased since the withdrawal of sodium benzoate and arginine therapy at 7y |
