C9orf72 and amyotrophic lateral sclerosis: These genes include TAR DNA binding protein (TARDBP/TDP-43), superoxide dismutase 1 (SOD1), FUS RNA binding protein (FUS/TLS), or the most recently discovered gene C9orf72-SMCR8 complex subunit (C9orf72) with ALS-causing hexanucleotide repeat expansions [1,2,3].