Abstract
Objective: Urea cycle disorders (UCDs) are inherited deficiencies of the enzymes or transport molecules involved in the
cellular excretion of excess ammonia produced during protein metabolism. The aim of this study was to evaluate the
clinical characteristics and long-term outcome of pediatric patients with UCDs.
Material and Methods: Our research was conducted between September 2020-March 2021 in Dr. Sami Ulus
Maternity and Child Health Training and Research Hospital. Clinical characteristics in 16 patients with UCDs [carbamoyl
phosphate synthetase I deficiency (n=1), N-acetylglutamate synthase deficiency(n=1), argininosuccinate lyase deficiency
(n=4), argininosuccinate synthetase deficiency (n=4), arginase deficiency (n=2), ornithine transcarbamylase deficiency
(n=2), hyperammonemia hyperornithinemia homocitrullinuria syndrome (n=2)] were defined. The term “neonatal-onset”
UCD was used if symptoms occurred within 28 days of life, and “late-onset” if symptoms started after the neonatal
period.
Results: Eight patients presented with acute metabolic crisis during newborn period. Core clinical phenotype in
neonatal-onset UCDs included sepsis-like findings, whereas epilepsy and mental retardation was predominant in lateonset
UCDs. For patients with neonatal-onset UCDs, hyperammonemia was more severe at the initial period.
Conclusion: Despite evolving treatment opportunities, still high mortality rates were found in neonatal-onset UCD. UCDs
should be suspected in pediatric patients with hyperammonemia and metabolic investigations should be performed
immediately to enlighten diagnosis. Neonatal-onset UCD usually present with symptoms of acute hyperammonemia, while
moresubtle neurological manifestations are frequent initial findings in the late onset UCD.
Keywords: hyperammonemia, neonatal, Inborn urea cycle disorders
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