A female infant, weighing 2786 g, was born at 39 weeks gestational age with Apgar scores of 8 points at 1 min and 9 points at 5 min after birth. She had no family history of hereditary disorders. Although she had no medical problems at birth and consumed her mother’s breast milk, she developed fever with increased white blood cell counts (WBC: 22,070/μL) and C-reactive protein level (CRP: 1.2 mg/dL) at 2 days after birth. Bacterial infection was suspected, and she received antibiotic therapy. Subsequently, she developed jaundice, convulsions, and respiratory failure and required respiratory support. As the doctors were concerned about a risk of neonatal herpes infection, she received γ-globulin and acyclovir treatments. In addition, she developed mild acidosis and hyperammonemia >400 μg/dL (normal range: 30–80 μg/dL). Urea cycle disorders were suspected, and she was treated with arginine, sodium benzoate, and high glucose infusion. Unfortunately, her plasma ammonia level increased to 2000 μg/dL at 3 days after birth (Fig. 12.1), and she was transferred to a neonatal intensive care unit for treatment with hemodialysis and possible liver transplantation. Her blood ammonia levels gradually improved and normalized at 21 days after birth. Her blood glutamine, glutamic acid, glycine, aspartic acid, citrulline, and arginine levels were 3262 μmol/L (control: 416–740 μmol/L), 265 μmol/L (12–83 μmol/L), 705 μmol/L (140–427 μmol/L), 29 μmol/L (trace–7.2 μmol/L), trace (18–48 μmol/L), and 69 μmol/L (32–150 μmol/L), respectively. The results of the neonatal tandem mass spectrometry screening test for inherited metabolic diseases and analysis test for urinary orotic acid were negative. She was definitively diagnosed with carbamoyl phosphate synthetase 1 deficiency (CPSD) by identification of a mutation of the carbamoyl phosphate synthetase 1 gene (c.2339G>A and c.2945G>A). She underwent a living donor liver transplantation with her father as the donor at the age of 6 months. The subject is presently 7 years and 5 months old, attends primary school, and lives a stable life.
KeywordsAmmonia Amino acids Orotic acid Neonatal onset Late onset
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