To elucidate the molecular mechanisms underlying the extra-neural pathology of ALS, some authors focus on TAR DNA-binding protein 43 kDa (TDP-43) which is found in 90–95% of sporadic ALS patients, and that in familial ALS is linked to TAR DNA-binding protein (TARDBP) or C9orf72-SMCR8 Complex Subunit (C9ORF72) genes. This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.