This study is testing a medicine called **GTX-102** to see if it helps kids with **Angelman Syndrome (AS)** think better. AS is a rare genetic disorder caused by a missing part of the **UBE3A gene**. Kids with AS have trouble with motor skills and mental development. In this study, kids will take GTX-102 and doctors will check if their thinking improves. The study is a **Phase 3 trial**, which means the medicine has been tested before and it's safe enough for more people to try.

To join, participants must be able to walk, even if they need help. They can't be in a wheelchair all the time. They need to have a confirmed AS diagnosis, and their parents must agree to the study. Some health tests will be done to make sure it's safe for them to participate. Kids and parents must follow the study rules, like making sure females use birth control if they could get pregnant. The study will look at their health for **at least 6 months** after the last dose of GTX-102.

• Participants must visit the study site for tests and check-ups.
• Some risks include reactions to the medicine or study procedures.
• Participants can't change any AS medications or diets a month before starting.