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X-linked ornithine transcarbamylase deficiency (OTCD) is the most common urea cycle defect. The disease severity ranges from asymptomatic carrier state to severe neonatal presentation with hyperammonaemic encephalopathy. We audited the diagnosis and management of OTCD, using an online 12-question-survey that was sent to 75 metabolic centres in Turkey, France and the UK. Thirty-nine centres responded and 495 patients were reported in total. A total of 208 French patients were reported, including 71 (34%) males, 86 (41%) symptomatic and 51 (25%) asymptomatic females. Eighty-five Turkish patients included 32 (38%) males, 39 (46%) symptomatic and 14 (16%) asymptomatic females. Out of the 202 UK patients, 66 (33%) were male, 83 (41%) asymptomatic and 53 (26%) symptomatic females. A total of 19%, 12% and 7% of the patients presented with a neonatal-onset phenotype in France, Turkey and the UK, respectively. Vomiting, altered mental status and encephalopathy were the most common initial symptoms in all three countries. While 69% in France and 79% in Turkey were receiving protein restriction, 42% were on a protein-restricted diet in the UK. A total of 76%, 47% and 33% of patients were treated with ammonia scavengers in Turkey, France and the UK, respectively. The findings of our audit emphasize the differences and similarities in manifestations and management practices in three countries.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by lack of social interaction, limited areas of interest, and repetitive behaviors. Comprehensive screening studies have shown that the prevalence of ASD is increasing. Arginase deficiency is an autosomal recessive metabolic disorder that affects the last step of the urea cycle. In this report, clinical features, neurological findings and genetic analysis results of an 11-year-old boy diagnosed with ASD have been discussed. Additionally, accompanying late diagnosed arginase deficiency has been also highlighted. In addition to the coexistence of ASD and metabolic diseases, the importance of early diagnosis and treatment in such cases has been emphasized.

Aim:Urea cycle disorders (UCD) still have poor neurological outcomes despite early diagnosis and treatment. We aimed to present the neurological outcomes of UCD patients and to determine the main simple and accessible factors affecting these outcomes.Materials and Methods:This was a descriptive cross-sectional study conducted in two pediatric metabolism centers on 29 patients from 25 unrelated families who were diagnosed and followed with UCD based on clinical presentation, neurological parameters, biochemical measurements, and molecular analysis.Results:Within the study population, the most common diagnosis was argininosuccinate synthase deficiency in 13 (44.82%) patients, followed by N-acetylglutamate synthase deficiency in five patients (17.24%), ornithine transcarbamylase deficiency in four patients (13.79%), arginase 1 deficiency in three patients (10.34%), carbamoyl phosphate synthase 1 deficiency in three patients (10.34%), and argininosuccinate lyase deficiency in one patient (3.44%). Peak ammonia levels were observed to be significantly higher in those patients with delayed milestones and patients who had Denver II 500 μmol/L (n=18). Those patients with abnormal neurological parameters had a significantly higher mean number of hyperammonemic episodes per year. Extracorporeal detoxification was given to eight patients, in combination with therapeutic hypothermia in two patients. Rapid regression was observed in brain edema in those who underwent therapeutic hypothermia.Conclusion:Our study emphasizes the effect of peak ammonia levels and the frequency of hyperammonemic episodes on neurological outcomes. There were still poor neurocognitive outcomes despite extracorporeal detoxification. This highlights the need to reassess current treatment strategies, including the threshold for starting extracorporeal detoxification if ammonia levels exceed 500 µmol/L. The use of therapeutic hypothermia by experienced teams may be promising due to its brain edema-reducing effects.