Clinical and Biochemical Characterizations of Pediatric Patients with Urea Cycle Disorders in Upper Egypt: A Case- Control Study

Background: The diagnosis of inborn errors of metabolism is generally challenging. We aimed to explore various types of urea cycle disorders (UCDs), and their clinical presentations and biochemical findings among Egyptian pediatric patients. Materials and Methods: This case-control study was conducted on 86 participants categorized into 43 pediatric patients suspected to have UCDs and 43 age- and sex-matched healthy controls, recruited from the Pediatric Outpatient Clinics, Inpatients Pediatric Departments, PICU and Neonatal Intensive Care Units of Qena, Assiut and Aswan University Hospitals, Egypt. In addition to the clinical assessments and routine laboratory investigations, colorimetric assays of blood lactate and ammonia, and plasma free amino acids assays using high performance liquid chromatography (HPLC), were performed for all included children. For patients with abnormal aminograms, the five enzymes of the urea cycle were measured in their liver tissue homogenates, using chemical methods. Results: The results showed that 25 out of 43 suspected patients were confirmed to have UCDs. The most frequent type of UCDs was Ornithine transcarbamylase (OTC) deficiency (48%), followed by Argininosuccinate synthase (ASS) deficiency (36%) and the least frequent was arginase (ARG) deficiency (16%). The main clinical presentations were poor oral intake (100%), followed by lethargy (96%), hypotonia (68%), vomiting (64%), and hepatomegaly (48%). There were normal glucose and ABG values with significantly higher ammonia; lactate and the measured plasma free amino acids among patients with UCDs vs. the controls (p˂0.05). Conclusion: The most frequent types of UCDs among pediatric patients in Upper Egypt were OTC and ASS deficiencies. In addition to clinical suspicion, assays of lactate, ABG, glucose, ammonia and aminogram may be helpful biochemical tests in diagnosing UCDs.