A Study to Investigate the Safety, Tolerability, Pharmacokinetics (PK) and Pharmacodynamics (PD) of RO7248824 in Participants With Angelman Syndrome (AS)

Inclusion Criteria: * The participant has a parent, caregiver or legal representative (hereinafter "caregiver") who is reliable, competent and at least 18 years of age. The caregiver is willing and able to accompany the participant to clinic visits and to be available to the Investigational Site by phone or email if needed and who (in the opinion of the Investigator) is and will remain sufficiently knowledgeable of participant's ongoing condition to respond to any inquiries about the participant from personnel from the Study Site. * A caregiver must be able to consent for the participant according to International Council on Harmonisation (ICH) and local regulations. * Ability to comply with all study requirements. * Have adequate supportive psychosocial circumstances. * Able to tolerate blood draws. * Able to undergo lumbar puncture (LP) and IT injection, under sedation or anesthesia if needed and as determined appropriate by the Investigator. * Stable medical status for at least 4 weeks prior to Screening and at the time of enrollment. * Body weight of ≥ 7 kg * Participant must be ≥ 1 to ≤ 12 years of age at the time of signing of the informed consent by the caregiver. * Clinical diagnosis of AS confirmed by a molecular diagnosis with genotypic classification of either Ubiquitin-protein ligase E3A (UBE3A) mutation of the maternal allele or deletion on the maternally inherited chromosome 15q11q13 that includes the UBE3A gene and is less than 7 megabyte (Mb) in size. Reprod…