The present invention relates to adeno-associated viral (AAV) particles encoding siRNA molecules and methods for treating amyotrophic lateral sclerosis (ALS). The present invention relates to compositions, methods and processes for the design, preparation, manufacture, use and/or formulation of AAV particles comprising modulatory polynucleotides, e.g., polynucleotides encoding at least one small interfering RNA (siRNA) molecules which target the superoxide dismutase 1 (SOD1) gene. Methods for using the AAV particles to inhibit the expression of the SOD1 gene in a subject with a neurodegenerative disease (e.g., amyotrophic lateral sclerosis (ALS)) are also disclosed.
