An Open-Label First-in-Human Phase 1/2 Study to Evaluate the Safety, Tolerability, and Efficacy of FRF-001, an AAV-9 Gene Therapy Administered by Intracerebroventricular Injection in Participants With FOXG1 Syndrome

Inclusion Criteria: * Participant must have a FOXG1 mutation confirmed as likely pathogenic or pathogenic by whole exome sequencing, whole genome sequencing, gene panel, single gene testing, or microarray performed at an accredited lab, with clinical phenotype consistent with FS in the opinion of the investigator. * The participant, or the participant's parent or legal guardian, is registered at the time of signing the informed consent in the FRF Citizen Natural History Study. * The participant, or the participant's parent, legal guardian, or caregiver are willing and able to complete all asp…