Ornithine Transcarbamylase (OTC) deficiency, the most common urea cycle disorder, is an inherited metabolic disorder caused by a genetic defect in a liver enzyme responsible for detoxification of ammonia. Individuals with OTC deficiency can build-up excess levels of ammonia in their blood, potentially resulting in devastating consequences, including cumulative and irreversible neurological damage, coma and death. The severe form of the condition emerges shortly after birth and is more common in boys than girls. This is a Phase 1/2/3, open-label, multicenter, safety, efficacy, and dose finding study of ECUR-506 in male babies with neonatal onset OTC deficiency. The primary objective of this study is to evaluate the safety, tolerability, and efficacy of up to three dose levels of ECUR-506 following intravenous (IV) administration of a single dose.