The study focuses on Limb Girdle Muscular Dystrophy Type 2I, a rare genetic condition that causes progressive weakness of the muscles around the hips and shoulders. The experimental medication being examined is called BBP-418 (Ribitol), which is taken as a powder that is mixed with water to make an oral solution. This drug is designed to replace a missing building block in the muscle cells, potentially helping the muscles work better over time.

The main goal is to see whether long‑term use of the medication is safe and whether it continues to provide clinical benefit for people with this condition. Participants will receive the study drug every day for several years and will attend regular clinic visits where they will be asked about any side effects, have simple physical tests such as walking speed measured with the 10MWT, and undergo breathing assessments using the FVC test, which checks how well the lungs can move air in and out while sitting. Blood samples will also be taken to monitor levels of serum CK, an enzyme that rises when muscle damage occurs.

During the study, researchers will track changes in muscle strength, walking ability, and breathing function from the start of the trial to its end. Any new health problems or worsening of existing symptoms will be recorded, and the overall safety of the medication will be closely monitored throughout the study period.