C9orf72 and amyotrophic lateral sclerosis: Currently, variants in more than 120 genes have been linked to ALS (Mathis et al., 2019; Chen et al., 2022; Nijs and Van Damme, 2024), including superoxide dismutase 1 (SOD1), chromosome 9 open reading frame 72 (C9orf72), Fused in Sarcoma (FUS), and TAR DNA binding protein (TARDBP, encoding TDP-43) (Al-Chalabi and Hardiman, 2013; Ling, 2018).