This is a Phase 1-2a, open-label study consisting of 2 parts. Part 1 is a multiple ascending dose (MAD) study, consisting of a 13-week MAD Treatment Period and a minimum 12-week but up to 32-week Post-MAD Follow-Up Period. Part 2 is the Long-Term Extension (LTE) Period including a 49-week LTE Treatment Period, where participants who completed Part 1 will receive IT bolus doses of ION582 and a 32-week Post-LTE Follow-Up Period. The study will enroll approximately 44, and up to 55 participants.
The purpose of this study is to evaluate the safety and tolerability of ascending doses of ION582 administered intrathecally in participants with Angelman syndrome.