Researchers are studying a treatment called **INS1201** to see if it's safe for boys who can walk and have a condition called **Duchenne Muscular Dystrophy (DMD)**. This condition makes muscles weaker over time. The study involves a single injection of INS1201 directly into the spine, which is known as an **intrathecal (IT) injection**. Boys who join the study need to be 2 to 5 years old and able to walk at least 10 meters without help. They also need to have a specific change in their **DMD gene** that affects a protein called **dystrophin**. Boys cannot join if they have had certain treatments before or have other health issues like heart problems or infections. This study does not involve gene or cell-based treatments.

• The study involves a single injection of the medication.
• Participants must be 2-5 years old and able to walk.
• Previous treatments or certain health conditions may exclude participation.