This clinical trial is focused on studying a rare genetic condition called X-linked Myotubular Myopathy (XLMTM). This condition affects muscle strength and function, primarily in young boys. The study is testing a new treatment called AT132, which is a type of gene therapy. Gene therapy involves using a specially designed virus to deliver a healthy copy of a gene into the body. In this case, the therapy uses a viral vector known as AAV serotype 8 to deliver the human MTM1 gene to patients. This approach aims to address the genetic cause of XLMTM by providing the body with the correct gene needed for muscle function.

The purpose of the study is to determine the best dose of AT132 and to confirm its safety and effectiveness in treating XLMTM. Participants in the study will receive the treatment through an intravenous infusion, which means the solution is delivered directly into the bloodstream. The study will follow participants over time to monitor changes in their condition, including their need for ventilator support and their ability to sit independently. Some participants may receive a placebo as part of the study design.

The study will take place over several years, with regular check-ups to assess the health and progress of the participants. Researchers will look at various health indicators, such as muscle strength, breathing ability, and overall quality of life, to understand how well the treatment works. The ultimate goal is to improve the lives of those affected by XLMTM by reducing symptoms and enhancing muscle function.