Zilganersen Expanded Access Program for Individuals With Alexander Disease

Key Inclusion Criteria: 1. Approved drug or drugs available for treatment did not work for the patient, or the patient cannot tolerate the side effects of the FDA-approved drug or drugs for treatment of AxD. 2. Patients who are ≥ 2 years old. 3. Patients who have a clinical phenotype and brain imaging consistent with a diagnosis of AxD. 4. Patients who have a documented variant in the GFAP gene. 5. Patient resides in and is a resident of the US. Key Exclusion Criteria: 1. Patients who have any medical history, physical exam findings, or clinically significant laboratory abnormalities that contraindicate performing an LP for ITB administration of zilganersen. 2. Patients who have current obstructive hydrocephalus. 3. Patients who have the presence of a functional ventriculoperitoneal shunt for the drainage of CSF. 4. Patients who have any other medical history or current conditions, which, in their Treating Physician's opinion, would make the patient unsuitable for inclusion (e.g., active Hepatitis B virus or hepatitis C virus infection, severe hepatic or renal disease, uncontrolled acute or chronic condition, etc.). 5. Patients who are pregnant or plan to become pregnant, or patients who are breastfeeding. Other inclusion/exclusion criteria may apply.