This study focuses on Propionic Acidemia, which is a rare genetic disorder that prevents the body from properly breaking down certain proteins. This condition can lead to a buildup of acid in the blood, which may cause health problems. The study aims to evaluate the long-term safety and clinical activity of mRNA-3927, an experimental treatment made of modified messenger ribonucleic acid. This substance is delivered through intravenous injection, which means it is administered directly into a vein, and it is packaged in lipid nanoparticles, which are tiny fat-based particles used to protect the medicine as it enters the body.

Participants in this study have previously been part of an earlier clinical trial. During this phase, they will continue to receive the treatment to monitor how the body reacts over a longer period. The focus is on tracking any side effects or changes in health to ensure the treatment remains safe for long-term use.