Fatal Coma in a Young Adult due to Late-Onset Urea Cycle Deficiency Presenting with a Prolonged Seizure: A Case Report

Ornithine transcarbamylase (OTC) deficiency is a urea cycle X-linked defect which considered the most prevalent inherited defect of the urea cycle. A very few reports of late-onset presentations in adults exist. Here, we report a previously healthy 17-year-old male who developed a prolonged seizure, a rapidly decline inmental status leading to coma over 3 days period. Analysis of the OTC gene showed a 119G variant, which was identified in exon 2 of the OTC gene by sequencing. A diagnosis of OTC deficiency should be considered in adult patients with unexplained hyperammonemic coma. This report highlights the pathophysiologic characteristics of this raredisorder, with this extremely rare presentation, clinical course, diagnosis and reviewthe therapeutic options.