Analysis of progression on functional endpoints over time for participants in the PRO-DMD natural history database

Duchenne muscular dystrophy (DMD) is a rare genetic disease that mostly affects boys, with about 20 out of every 100,000 male babies born worldwide having the condition. This leads to roughly 7 out of every 100,000 males living with DMD. The disease causes muscles in the body to weaken over time, including the heart and muscles used for movement. Children with DMD often lose the ability to walk during their early teenage years and may have a shortened lifespan. It is caused by changes in a gene called DMD, which provides instructions for making a protein called dystrophin. Dystrophin helps protect muscles from damage during movement. When there is little or no dystrophin, the muscles break down and are replaced by scar tissue and fat, making them weaker over time.

This research focuses on understanding how the disease progresses in smaller groups of DMD patients who have specific types of gene mutations. Some of these patients may be able to benefit from treatments that “skip” certain parts of the gene—called exons—so their bodies can make a shorter but still helpful version of the dystrophin protein. This study will look at how the disease progresses over time in patients whose mutations are suited to skipping exon 44 or exon 45.

We will analyze information from a previous study called PRO-DMD-01, which followed DMD patients over time. By closely examining how these smaller groups change in their physical abilities, we hope to better understand how the disease affects different people. This can help researchers design better clinical trials for future treatments—by setting more accurate goals, choosing the right measurement tools, and estimating how many participants are needed.

The results will support the development of new treatments being created by Avidity Biosciences, which uses a technology called antibody oligonucleotide conjugates (AOC). These treatments aim to address the root cause of DMD at the genetic level.