Study to Characterize Rate of Ureagenesis in Patients With Ornithine Transcarbamylase (OTC) Deficiency

Key Inclusion Criteria: * Willing and able to provide written informed consent. * For symptomatic patients: * Confirmed clinical diagnosis of OTC deficiency and enzymatic, biochemical, or molecular testing. * Documented history of ≥ 1 symptomatic hyperammonemic episode with ammonia level ≥ 100 μmol/L * Patients on ongoing daily ammonia scavenger therapy must be at a stable dose(s) for ≥ 4 weeks prior to Visit 1 (Baseline) * For asymptomatic patients: confirmed diagnosis of OTC deficiency by family history and documented by molecular testing. * Willing and able to comply with the study procedures and requirements, including clinic visits, blood and urine collections, questionnaires, and cognitive assessments. Key Exclusion Criteria: * Liver transplant, including hepatocyte cell therapy/transplant. * History of liver disease * Significant hepatic inflammation or cirrhosis * Participation in another investigational medicine study within 3 months of Screening * Participation (current or previous) in another gene transfer study * Pregnant or nursing Other protocol specific criteria may apply