TARDBP and amyotrophic lateral sclerosis: The most common genetic causes of ALS are the hexanucleotide repeat expansion (HRE) in the chromosome 9 open reading frame 72 (C9ORF72) gene1,2 and mutations in superoxide dismutase 1 (SOD1)3 TAR DNA-binding protein 43 (TARDBP)4 or fused in sarcoma (FUS).5,6 Several biological and cellular pathways are implicated in the onset and progression of ALS, leading to pathophysiological heterogeneity.