Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease characterized by progressive degeneration of motor neurons (MNs) in the brain and spinal cord.1 In the majority of patients, including those with TDP-43 (TARDBP) mutations and C9orf72 hexanucleotide expansions, TDP-43 protein mis-localizes to the cytoplasm and forms ubiquitinated and hyperphosphorylated aggregates,2–5 which has been linked to abnormal RNA metabolism and stability, as well as changes to RNA splicing and gene expression.1,6,7. Here, C9orf72 is linked to amyotrophic lateral sclerosis.