A Phase 1-2, Double-Blind, Sham-Controlled Multiple Ascending Dose Study to Evaluate Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Intrathecally-Administered ION440 in Patients With MECP2 Duplication Syndrome

Key Inclusion criteria for Part 1: 1. Males aged ≥ 2 to ≤ 65 years, depending on specific cohort and group, at the time of informed consent. 1. Group A: ≥ 8 to ≤ 65 years old 2. Group B: 2 to 7 years old, inclusive 2. Participant has at least one parent or caregiver ≥ 18 years old capable of providing informed consent and able to comply with all study requirements and activities. 3. Participant has a documented diagnosis of MDS with genetic confirmation of MECP2 duplication. 4. Is currently receiving stable doses of concomitant medications for at least 1 month prior to screening. 5. Ab…