C9orf72 and sarcoma: Despite the growing number and variety of these genes, four of them stand out as the most commonly mutated in ALS: superoxide dismutase 1 (SOD1), chromosome 9 open reading frame 72 (C9orf72), fused in sarcoma/translocated in liposarcoma (FUS/TLS), and TAR DNA-binding protein 43 (TARDBP-43) [16,19,20,21].