This study focuses on children under two years of age who have Arginase 1 Deficiency (ARG1-D), a rare genetic condition where the body cannot properly break down an amino acid called arginine. The study will test a medication called pegzilarginase, which is given as an injection under the skin once per week. This medicine is designed to help reduce the high levels of arginine in the blood that occur in people with this condition.

The purpose of this research is to evaluate how well pegzilarginase works in lowering arginine levels in the blood of young children with Arginase 1 Deficiency. The study will also look at how safe the medication is and how the body processes it. The treatment will continue for 12 weeks, during which children will receive weekly injections of pegzilarginase.

Throughout the study, doctors will monitor the children’s health through regular check-ups and blood tests. They will track various aspects of the children’s development, including their physical abilities and growth. The study will also check how the children’s bodies respond to the medication and whether they develop any reactions to the treatment.