Tofersen (BIIB067) is an ASOs targeting SOD1 mRNA by RNase H-dependent degradation (Smith et al., 2006; McCampbell et al., 2018; Rinaldi and Wood 2018) to reduce SOD1 protein concentrations in patients with ALS (Miller et al., 2020). The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.