After the identification of mutations in the SOD1 gene in 1993 (Rosen et al., 1993), more than 30 genes have been involved in the pathology, with the most common disease-causing variants in C9orf72, SOD1, FUS, and TARDBP. However, monogenic forms explain only a fraction of the diagnosed cases, suggesting ALS as a polygenic disease (McCann et al., 2017; Mejzini et al., 2019). The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.