Mutations in the SLC6A1 gene result in a form of pediatric epileptic encephalopathy, intellectual disability and autism spectrum disorder. Allison Bradbury and colleagues are evaluating AAV9-mediated gene replacement as a treatment for SLC6A-related disorders using delivery directly to the cerebrospinal fluid and targeting cell types of interest, neurons and astrocytes. They will perform a dose response study on a candidate vector and determine efficacy with additional clinically relevant readouts of seizure monitoring and electrophysiology.