This is caused by the accumulation of ALS-associated mutant proteins such as superoxide dismutase 1 (SOD1), transactive response (TAR) DNA binding protein 43 kDa (TDP-43), fused sarcoma, chromosome 9 open reading frame 72 (C9orf72) gene product, and the C9orf72 GGGGCC repeat expansion-associated glycine/arginine dipeptide repeat protein [242]. Here, C9orf72 is linked to amyotrophic lateral sclerosis.