Neuronal Ceroid Lipofuscinosis Cln6

The goal of this clinical trial is to learn if a gene therapy called scAAV9.CB.CLN6 can treat children with CLN6 Batten disease (variant late infantile neuronal ceroid lipofuscinosis). The main questions it aims to answer are if he gene therapy safe and well tolerated, and if the gene therapy help slow disease progression or improve symptoms. Participants will: Receive a single dose of the gene therapy through an injection into the fluid around the spinal cord (intrathecal administration) Have regular study visits over 2 years for safety checks and assessments of disease progression Be followed for an additional 3 years in a long-term follow-up study

This study aims to assess the natural history of Batten disease (Neuronal Ceroid Lipofuscinosis) by obtaining information about the motor, behavioral, and functional capabilities of individuals with Batten disease. This study will also refine and validate the Unified Batten Disease Rating Scale (UBDRS) as a clinical rating instrument for Batten disease.