To investigate whether an augmented expression of S100A4 is a common trait of fibroblasts derived from patients with ALS, we have analyzed the protein expression in primary fibroblasts from ALS patients without known variants in ALS-associated genes, and from patients carrying pathogenic C9orf72 expansions, the most common cause of familial and sporadic ALS found to date. This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.