Pathological proteins TDP‐43 and SOD1 in ALS form seeding aggregates (Johnson et al., 2009; Watanabe et al., 2001) that are believed to propagate via axonal pathways between connected regions leading to a stereotyped spread of disease in the brain (Jucker & Walker, 2013). The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.