Mitochondrial dysfunction was evident in fibroblasts of ALS patients carrying pathogenic mutations in SOD1 (I113T), in FUS1 (fused in sarcoma; R521G), or in TDP43 (TAR DNA‐binding protein 43; G289S) genes and was associated with an increased Drp1 association with the mitochondria. Here, SOD1 is linked to amyotrophic lateral sclerosis.